Question's 5
Question's 5
QUESTION'S
INTEGRATION
        QUESTIONS                                           1                                 TOPIC:8 INTEGRATION
                      1
                          √
    1    Evaluate         (3x + 1) dx.                                                                             [4]
                      0
                                                      18
         The diagram shows part of the graph of y =       and the normal to the curve at P (6, 3). This normal
                                                       x
         meets the x-axis at R. The point Q on the x-axis and the point S on the curve are such that PQ and SR
         are parallel to the y-axis.
(i) Find the equation of the normal at P and show that R is the point (4 12 , 0). [5]
          (ii) Show that the volume of the solid obtained when the shaded region PQRS is rotated through
               360◦ about the x-axis is 18π .                                                         [4]
                                  dy     6
3       A curve is such that         =√         and P (3, 3) is a point on the curve.
                                  dx   (4x − 3)
           (i) Find the equation of the normal to the curve at P, giving your answer in the form ax + by = c.
                                                                                                            [3]
                                              dy    d2 y
          (i) Write down expressions for         and 2 .                                                        [3]
                                              dx    dx
(ii) Find the coordinates of the stationary point on the curve and determine its nature. [4]
         (iii) Find the volume of the solid formed when the region enclosed by the curve, the x-axis and the
               lines x = 1 and x = 2 is rotated completely about the x-axis.                             [6]
    QUESTIONS                                          2                                TOPIC:8 INTEGRATION
                            dy
5   A curve is such that       = 2x2 − 5. Given that the point (3, 8) lies on the curve, find the equation of
                            dx
      the curve.                                                                                          [4]
                               4
6    A curve has equation y = √ .
                                x
       (i) The normal to the curve at the point (4, 2) meets the x-axis at P and the y-axis at Q. Find the
           length of PQ, correct to 3 significant figures.                                             [6]
(ii) Find the area of the region enclosed by the curve, the x-axis and the lines x = 1 and x = 4. [4]
                            dy 16
7   A curve is such that      =   , and (1, 4) is a point on the curve.
                            dx x3
      (ii) A line with gradient − 12 is a normal to the curve. Find the equation of this normal, giving your
           answer in the form ax + by = c.                                                               [4]
(iii) Find the area of the region enclosed by the curve, the x-axis and the lines x = 1 and x = 2. [4]
                           dy      4
8   A curve is such that      =√         , and P (1, 8) is a point on the curve.
                           dx   (6 − 2x)
      (i) The normal to the curve at the point P meets the coordinate axes at Q and at R. Find the
          coordinates of the mid-point of QR.                                                  [5]
    The diagram shows the curve y = x3 − 3x2 − 9x + k, where k is a constant. The curve has a minimum
    point on the x-axis.
(ii) Find the coordinates of the maximum point of the curve. [1]
(iii) State the set of values of x for which x3 − 3x2 − 9x + k is a decreasing function of x. [1]
10
      The diagram shows the curve y = x(x − 1)(x − 2), which crosses the x-axis at the points O (0, 0),
      A (1, 0) and B (2, 0).
        (i) The tangents to the curve at the points A and B meet at the point C. Find the x-coordinate of C.
                                                                                                          [5]
       (ii) Show by integration that the area of the shaded region R1 is the same as the area of the shaded
            region R2 .                                                                                  [4]
                                         6
11    The equation of a curve is y =          .
                                       5 − 2x
(i) Calculate the gradient of the curve at the point where x = 1. [3]
      (ii) A point with coordinates (x, y) moves along the curve in such a way that the rate of increase of
           y has a constant value of 0.02 units per second. Find the rate of increase of x when x = 1.  [2]
      (iii) The region between the curve, the x-axis and the lines x = 0 and x = 1 is rotated through 360◦
            about the x-axis. Show that the volume obtained is 12
                                                                5
                                                                  π.                                   [5]
12
                                              1
      The diagram shows the curve y = 3x 4 . The shaded region is bounded by the curve, the x-axis and
      the lines x = 1 and x = 4. Find the volume of the solid obtained when this shaded region is rotated
      completely about the x-axis, giving your answer in terms of π .                                 [4]
     QUESTIONS                                            4                               TOPIC:8 INTEGRATION
                                            8
 13     The equation of a curve is y = 2x + .
                                           x2
                                       dy    d2 y
        (i) Obtain expressions for        and 2 .                                                               [3]
                                       dx    dx
        (ii) Find the coordinates of the stationary point on the curve and determine the nature of the stationary
             point.                                                                                           [3]
       (iii) Show that the normal to the curve at the point (−2, −2) intersects the x-axis at the point (−10, 0).
                                                                                                              [3]
(iv) Find the area of the region enclosed by the curve, the x-axis and the lines x = 1 and x = 2. [3]
                                                               √
 14     Find the area of the region enclosed by the curve y = 2 x, the x-axis and the lines x = 1 and x = 4.
                                                                                                           [4]
                           dy
15      A curve is such that   = 4 − x and the point P (2, 9) lies on the curve. The normal to the curve at P
                           dx
       meets the curve again at Q. Find
        (i) the equation of the curve,                                                                          [3]
        (ii) the equation of the normal to the curve at P,                                                      [3]
       (iii) the coordinates of Q.                                                                              [3]
16
                                   y
(1, 18)
(4, 3)
                                                                                      x
                               O            1       1.6
                                                dy     k
      The diagram shows a curve for which          = − 3 , where k is a constant. The curve passes through the
                                                dx    x
      points (1, 18) and (4, 3).
                                                                         16
       (i) Show, by integration, that the equation of the curve is y =      + 2.                            [4]
                                                                         x2
      The point P lies on the curve and has x-coordinate 1.6.
17
                                            y
                                                             Q   y = Ö (3x + 1)
                                        2
1 P
                                                                                  x
                                        O                    1
                                         √
       The diagram shows the curve y = (3x + 1) and the points P (0, 1) and Q (1, 2) on the curve. The
       shaded region is bounded by the curve, the y-axis and the line y = 2.
(ii) Find the volume obtained when the shaded region is rotated through 360◦ about the x-axis. [4]
(iii) Find the acute angle, in degrees correct to 1 decimal place, between the two tangents. [4]
(i) Find the coordinates of the stationary point on the curve and determine its nature. [4]
(ii) Find the area of the region enclosed by the curve, the x-axis and the lines x = 0 and x = 1. [3]
                              dy      1
19     A curve is such that      = 3x 2 − 6 and the point (9, 2) lies on the curve.
                              dx
        (i) Find the equation of the curve.                                                                  [4]
       (ii) Find the x-coordinate of the stationary point on the curve and determine the nature of the
            stationary point.                                                                      [3]
     QUESTIONS                                                6                                 TOPIC:8 INTEGRATION
 20
                                             y
                                                                     a
                                                                  y= x
                                                                                        x
                                         O               1                 3
                                                  a
        The diagram shows part of the curve y =     , where a is a positive constant. Given that the volume
                                                  x
        obtained when the shaded region is rotated through 360◦ about the x-axis is 24π , find the value of a.
                                                                                                           [4]
 21
                                                 y
                                                                                                2
                                                                                    y = (x – 2)
                                     A
y + 2x = 7
                                                                       B
                                                                                            x
                                             O
        The diagram shows the curve y = (x − 2)2 and the line y + 2x = 7, which intersect at points A and B.
        Find the area of the shaded region.                                                              [8]
                                                     dy       6
22    The equation of a curve is such that              = √          . Given that the curve passes through the point
                                                     dx     (3x − 2)
      P (2, 11), find
        (i) the equation of the normal to the curve at P,                                                             [3]
       (ii) the equation of the curve.                                                                                [4]
     QUESTIONS                                              7                                      TOPIC:8 INTEGRATION
23
                                   y
y = x + 4x
                                                                                         y=5
                                        A                           B
                                                M
                                                                                               x
                                O
                                                   4
       The diagram shows part of the curve y = x + which has a minimum point at M . The line y = 5
                                                   x
       intersects the curve at the points A and B.
(ii) Find the volume obtained when the shaded region is rotated through 360◦ about the x-axis. [6]
                                   dy
        (i) Find an expression for    and determine, with a reason, whether the curve has any stationary
                                   dx
            points.                                                                                  [3]
       (ii) Find the volume obtained when the region bounded by the curve, the coordinate axes and the
            line x = 1 is rotated through 360◦ about the x-axis.                                   [4]
      (iii) Find the set of values of k for which the line y = x + k intersects the curve at two distinct points.
                                                                                                              [4]
25                               y
                                                                        x=5
                                    A
                                                                                          1
                                                                                  y=
                                                                          B                    1
                                                                                       (3x + 1)4
                                                                                              x
                               O
                                                        1
      The diagram shows part of the curve y =                   1
                                                                    . The curve cuts the y-axis at A and the line x = 5
                                                    (3x + 1) 4
      at B.
       (ii) Find the volume obtained when the shaded region is rotated through 360◦ about the x-axis. [9]
     QUESTIONS                                           8                                   TOPIC:8 INTEGRATION
(i) Find the set of values of x for which f is an increasing function. [3]
(ii) Given that the curve passes through (1, 3), find f (x). [4]
27
                                 y
y = 9 – x3
                                                                   Q               8
                                                                              y=
                                                                                   x3
                                                                                         x
                               O                 a                b
                                                                      8
      The diagram shows parts of the curves y = 9 − x3 and y =           and their points of intersection P and Q.
                                                                      x3
      The x-coordinates of P and Q are a and b respectively.
       (i) Show that x = a and x = b are roots of the equation x6 − 9x3 + 8 = 0. Solve this equation and
           hence state the value of a and the value of b.                                             [4]
(ii) Find the area of the shaded region between the two curves. [5]
      (iii) The tangents to the two curves at x = c (where a < c < b) are parallel to each other. Find the
            value of c.                                                                                [4]
      (ii) The region enclosed by the curve, the x-axis and the y-axis is rotated through 360◦ about the
           x-axis. Find the volume obtained, giving your answer in terms of π .                      [4]
                             dy     3
29    A curve is such that      =         and the point (1, 21 ) lies on the curve.
                             dx (1 + 2x)2
      (ii) Find the set of values of x for which the gradient of the curve is less than 13 .                   [3]
     QUESTIONS                                           9                               TOPIC:8 INTEGRATION
31
                                y
                                          M
                                                              y = 4 Öx – x
                                                                                          x
                            O                                                   A
                                               √
      The diagram shows part of the curve y = 4 x − x. The curve has a maximum point at M and meets
      the x-axis at O and A.
       (ii) Find the volume obtained when the shaded region is rotated through 360◦ about the x-axis, giving
            your answer in terms of π .                                                                  [6]
                          2x3 + 5
32    (a) Differentiate           with respect to x.                                                        [3]
                             x
                                                              1
      (b) Find ã (3x − 2)5 dx and hence find the value of ã (3x − 2)5 dx.                                   [4]
                                                              0
                            dy    2
33   A curve is such that      = √ − 1 and P (9, 5) is a point on the curve.
                            dx     x
(ii) Find the coordinates of the stationary point on the curve. [3]
                                    d2 y
     (iii) Find an expression for        and determine the nature of the stationary point.                  [2]
                                    dx2
     (iv) The normal to the curve at P makes an angle of tan−1 k with the positive x-axis. Find the value
          of k.                                                                                       [2]
34    A function f is defined for x ∈ > and is such that f ′ (x) = 2x − 6. The range of the function is given by
      f (x) ≥ −4.
(i) State the value of x for which f (x) has a stationary value. [1]
35
                             y
                                                                                          y = Ö(1 + 2x)
                                                                               C
                                                                                                  x
                     A           O
                                           √
      The diagram shows the curve y = (1 + 2x) meeting the x-axis at A and the y-axis at B. The
      y-coordinate of the point C on the curve is 3.
(iii) Find the volume obtained when the shaded region is rotated through 360◦ about the y-axis. [5]
                           dy       8
36    A curve is such that    = 5 − 2 . The line 3y + x = 17 is the normal to the curve at the point P on the
                           dx       x
      curve. Given that the x-coordinate of P is positive, find
       (i) the coordinates of P,                                                                              [4]
       (ii) the equation of the curve.                                                                        [4]
                                    √
37    The equation of a curve is y = (8x − x2 ). Find
                                 dy
       (i) an expression for        , and the coordinates of the stationary point on the curve,               [4]
                                 dx
       (ii) the volume obtained when the region bounded by the curve and the x-axis is rotated through
            360◦ about the x-axis.                                                                  [4]
38    A curve y = f (x) has a stationary point at P (3, −10). It is given that f ′ (x) = 2x2 + kx − 12, where k is
      a constant.
(i) Show that k = −2 and hence find the x-coordinate of the other stationary point, Q. [4]
(ii) Find f ′′ (x) and determine the nature of each of the stationary points P and Q. [2]
39
                                                                     y
y = Ö(x + 1)
y=x+1
                                    –1                                                 x
                                                                   O
                                                             √
       The diagram shows the line y = x + 1 and the curve y = (x + 1), meeting at (−1, 0) and (0, 1).
(ii) Find the volume obtained when the shaded region is rotated through 360◦ about the y-axis. [7]
40
                               y
                                            2
                                    y=
                                         Ö(x + 1)
y=1
                                                                                       x
                              O
      (ii) Find ä       − 1 dy. Hence find the area of the shaded region.
                      4
                                                                                                             [5]
                      y2
      (iii) The shaded region is rotated through 360◦ about the y-axis. Find the exact value of the volume
            of revolution obtained.                                                                     [5]
     QUESTIONS                                        12                                    TOPIC:8 INTEGRATION
41
                                            y
                                                           y=     6
                                                                2x – 3
                                                                              x
                                           O          2    3
                                                                   6
       The diagram shows the region enclosed by the curve y =           , the x-axis and the lines x = 2 and
                                                                 2x − 3
       x = 3. Find, in terms of π , the volume obtained when this region is rotated through 360◦ about the
       x-axis.                                                                                            [4]
42
                                   y
                                                            A
y = –x2 + 8x –10
                                                                                       x
                                 O
       The diagram shows part of the curve y = −x2 + 8x − 10 which passes through the points A and B. The
       curve has a maximum point at A and the gradient of the line BA is 2.
       (ii) Find ã y dx and hence evaluate the area of the shaded region.                                         [4]
     QUESTIONS                                              13                            TOPIC:8 INTEGRATION
43
                              y
                                  A
                             1                                   B (6, 1)               8
                                                                               x=          –2
                                                                                        y2
                                                                                    x
                             O
                                                8
      The diagram shows part of the curve x =     − 2, crossing the y-axis at the point A. The point B (6, 1)
                                               y2
      lies on the curve. The shaded region is bounded by the curve, the y-axis and the line y = 1. Find the
      exact volume obtained when this shaded region is rotated through 360◦ about the y-axis.             [6]
                             d2 y
44    A curve is such that        = −4x. The curve has a maximum point at (2, 12).
                             dx2
       (i) Find the equation of the curve.                                                                  [6]
      A point P moves along the curve in such a way that the x-coordinate is increasing at 0.05 units
      per second.
       (ii) Find the rate at which the y-coordinate is changing when x = 3, stating whether the y-coordinate
            is increasing or decreasing.                                                                 [2]
                              dy     8
45    A curve is such that       = − 3 − 1 and the point (2, 4) lies on the curve. Find the equation of the
                              dx    x
      curve.                                                                                            [4]
46
                                      y
                                                                      3y = 2x – 1
y2 = 2x – 1
                                      O                                             x
                                          1                      a
                                          2
      The diagram shows the curve y2 = 2x − 1 and the straight line 3y = 2x − 1. The curve and straight line
      intersect at x = 12 and x = a, where a is a constant.
      (ii) Find, showing all necessary working, the area of the shaded region.                              [6]
     QUESTIONS                                           14                              TOPIC:8 INTEGRATION
47
                                         y
B (0, 3)
                                                 y=     9
                                                      2x + 3
                                     C                         A (3, 1)
                                                                              x
                                     O
                                                  9
      The diagram shows part of the curve y =          , crossing the y-axis at the point B (0, 3). The point
                                                2x + 3
      A on the curve has coordinates (3, 1) and the tangent to the curve at A crosses the y-axis at C.
      (iii) Find, showing all necessary working, the exact volume obtained when the shaded region is
            rotated through 360◦ about the x-axis.                                               [4]
                                                      dy       4
48 A curve is defined for x > 0 and is such that         = x + 2 . The point P (4, 8) lies on the curve.
                                                      dx      x
       (i) Find the equation of the curve.                                                                 [4]
       (ii) Show that the gradient of the curve has a minimum value when x = 2 and state this minimum
            value.                                                                                 [4]
                  d2 y
       (i) Find        .                                                                                   [2]
                  dx2
       (ii) Verify that the curve has a stationary point when x = −1 and determine its nature.             [2]
      (iii) It is now given that the stationary point on the curve has coordinates (−1, 5). Find the equation
            of the curve.                                                                                 [5]
     QUESTIONS                                          15                                        TOPIC:8 INTEGRATION
50
                                    y
                                                                                              2
                                                                                   y = x(x – 2)
                                O                                                                 x
                                                b                    a
       The diagram shows the curve with equation y = x(x − 2)2 . The minimum point on the curve has
       coordinates (a, 0) and the x-coordinate of the maximum point is b, where a and b are constants.
                            dy
       (iv) The gradient,      , of the curve has a minimum value m. Find the value of m.                               [4]
                            dx
                                                                 1         − 12
51     A curve has equation y = f x and is such that f ′ x = 3x 2 + 3x          − 10.
                                                1
        (i) By using the substitution u = x 2 , or otherwise, find the values of x for which the curve y = f x
            has stationary points.                                                                          [4]
(ii) Find f ′′ x and hence, or otherwise, determine the nature of each stationary point. [3]
(iii) It is given that the curve y = f x passes through the point 4, −7. Find f x. [4]
52
                                            y
C A (1, 1) y = (x – 2)4
                                                                                          x
                                        O           B
      The diagram shows part of the curve y = x − 24 and the point A 1, 1 on the curve. The tangent at
      A cuts the x-axis at B and the normal at A cuts the y-axis at C.
                              dy   6
53    A curve is such that       = 2 and 2, 9 is a point on the curve. Find the equation of the curve.       [3]
                              dx x
54
                                                 y
                                                                    y = Ö(1 + 4x)
                                                                                        x
                                         A       O                             C
                                        
      The diagram shows the curve y = 1 + 4x , which intersects the x-axis at A and the y-axis at B. The
      normal to the curve at B meets the x-axis at C. Find
        (i) the equation of BC,                                                                                   [5]
       (ii) the area of the shaded region.                                                                        [5]
                              dy 
55     A curve is such that      = 2x + 5 and 2, 5 is a point on the curve. Find the equation of the curve.
                              dx
                                                                                                          [4]
56
                                                 y
A (1, 7)
                                                                  8
                                                            y=      –x
                                                                 Öx
                                                     C
                                                                    B (4, 0)        x
                                             O
                                                  8
      The diagram shows part of the curve y =  − x and points A 1, 7 and B 4, 0 which lie on the
                                                   x
      curve. The tangent to the curve at B intersects the line x = 1 at the point C.
                                                                     1      6
 57    A curve has equation y = f x. It is given that f ′ x =          + 2 and that f 3 = 1. Find f x. [5]
                                                                    x + 6 x
 58
                               y
y = (3 – 2x)3
(12 , 8)
                                                                                         x
                             O
                                                                                              1     
       The diagram shows the curve y = 3 − 2x3 and the tangent to the curve at the point      2
                                                                                                   ,8 .
(i) Find the equation of this tangent, giving your answer in the form y = mx + c. [5]
        (i) Find the gradient of the curve at the point where x = 2.                                        [3]
                                                          3
60
                                       y
                                                              C      y = 8x + 2x
                                              A
                                                   B
                                                                                   x
                                     O
     QUESTIONS                                             18                                    TOPIC:8 INTEGRATION
     The diagram shows part of the curve y =           + 2x and three points A, B and C on the curve with
                                                     8
                                                     x
     x-coordinates 1, 2 and 5 respectively.
      (i) A point P moves along the curve in such a way that its x-coordinate increases at a constant rate
          of 0.04 units per second. Find the rate at which the y-coordinate of P is changing as P passes
          through A.                                                                                   [4]
(ii) Find the volume obtained when the shaded region is rotated through 360Å about the x-axis. [6]
                                                                    − 32
61     A curve has equation y = f x. It is given that f ′ x = x          + 1 and that f 4 = 5. Find f x.           [4]
62
                                                           y
y = Ö(x 4 + 4x + 4)
                                                                                                       x
                                           –1            O
                                           
       The diagram shows the curve y =          x4 + 4x + 4 .
(i) Find the equation of the tangent to the curve at the point 0, 2. [4]
        (ii) Show that the x-coordinates of the points of intersection of the line y = x + 2 and the curve are
             given by the equation x + 22 = x4 + 4x + 4. Hence find these x-coordinates.                  [4]
       (iii) The region shaded in the diagram is rotated through 360Å about the x-axis. Find the volume of
             revolution.                                                                               [4]
                              dy     1    −1                                          
63     A curve is such that      = x 2 − x 2 . The curve passes through the point 4, 23 .
                              dx
        (i) Find the equation of the curve.                                                                            [4]
                    d2 y
        (ii) Find        .                                                                                             [2]
                    dx2
       (iii) Find the coordinates of the stationary point and determine its nature.                                    [5]
     QUESTIONS                                             19                              TOPIC:8 INTEGRATION
                                             d2 y
64    The equation of a curve is such that        = 2x − 1. Given that the curve has a minimum point at
                                             dx2
       3, −10, find the coordinates of the maximum point.                                          [8]
65
                                              y
                                                  y = 8 − ï 4 − x
                                                                 P 3, 7
                                                                             x
                                          O
                                                       
      The diagram shows part of the curve y = 8 −          4 − x and the tangent to the curve at P 3, 7.
                                   dy
        (i) Find expressions for      and Ó y dx.                                                                [5]
                                   dx
(ii) Find the equation of the tangent to the curve at P in the form y = mx + c. [2]
(iii) Find, showing all necessary working, the area of the shaded region. [4]
                           dy        12
66    A curve is such that    =            , where a is a constant. The point P 2, 14 lies on the curve and
                           dx      4x + a
      the normal to the curve at P is 3y + x = 5.
67
                                     y
y = 2x + 1
y = −x2 + 12x − 20
                                                                      x
                                   O
       The diagram shows the curve y = −x2 + 12x − 20 and the line y = 2x + 1. Find, showing all necessary
       working, the area of the shaded region.                                                         [8]