TTK - S AP Calculus AB
TTK - S AP Calculus AB
sin 2 x  cos2 x  1
1  tan2 x  sec 2 x
1  cot 2 x  csc 2 x
cos 2 x  2 cos2 x  1
cos 2 x  1  2 sin 2 x
                                                1  cos 2 x
                                    sin 2 x 
                                                     2
                                                1  cos 2 x
                                    cos2 x 
                                                     2
                               𝜋 𝜋
arcsin 𝜃 output will be in [− 2 , 2 ]
                                𝜋 𝜋
arctan 𝜃 output will be in (− 2 , 2 )
                                𝜋         𝜋
arcsec 𝜃 output will be in [0, 2 ) ∪ ( 2 , 𝜋]
                                𝜋                𝜋
arccsc 𝜃 output will be in [− 2 , 0) ∪ (0, 2 ]
                     Logarithm Properties
ln 1 = 0
ln e = 1
ln 𝑎 + ln 𝑏 = ln(𝑎𝑏)
                  𝑎
ln 𝑎 − ln 𝑏 = ln ( )
                  𝑏
𝑏 ln 𝑎 = ln(𝑎𝑏 )
𝑒 ln 𝑎 = 𝑎
Limit Existence
                          sin 𝑎𝑥                                𝑎𝑥
                    lim     𝑎𝑥
                                   =1                    lim          =1
                    𝑥→0                                  𝑥→0 sin 𝑎𝑥
Horizontal Asymptotes
NOTE: Horizontal asymptotes only exist at the ends of the graph. Therefore, the max number of
         horizontal asymptotes is 2. There can be 2, 1, or 0 horizontal asymptotes.
NOTE: Determining the limits above for ∞ and –∞ also tell you the end behavior on each side in
                    addition to determining the horizontal asymptotes.
                             constant
                                         = ±∞ (be careful of sign!)
                           approaching 0
                                        constant
                                                    =0
                                    approaching ± ∞
           NOTE: To check for continuity, you must find 𝑓(𝑐) and lim 𝑓(𝑥).
                                                                      𝑥→𝑐
If a function is continuous on [a, b], then it takes on every value between f(a) and f(b).
               Definitions of the Derivative
                                        𝑓(𝑥 + ℎ) − 𝑓(𝑥)
                                  lim
                                  ℎ→0          ℎ
                                        𝑓(𝑥) − 𝑓(𝑎)
                                    lim
                                    𝑥→𝑎    𝑥−𝑎
                                      𝑓(𝑎 + ℎ) − 𝑓(𝑎)
                                  lim
                                  ℎ→0        ℎ
REMEMBER! The derivative is the slope of the tangent line at that point on the graph.
    Tangent Line
          The slope of the tangent line is the derivative of the function.
          To find the slope of the tangent line at a particular point, find the
           derivative and then substitute the x-value into the result.
          To write the equation of the tangent line at a particular point, find the
           slope and then use point-slope form to write the equation of the line.
    Normal Line
          The normal line at a point is perpendicular to the tangent line at that
           point.
          To find the slope of the normal line, first find the slope of the tangent
           line. Then change the sign and take the reciprocal to determine the
           slope of the normal line.
                         Differentiability
A function f(x) is differentiable at x = c if the derivative from the left of x = c is
             equal to the derivative from the right of x = c. That is:
Horizontal tangents occur where the numerator of the derivative equals zero.
Vertical tangents occur where the denominator of the derivative equals zero.
          Critical Values & Relative Extrema
Definition of Critical Value
 Let f be defined at c. If f ′(c) = 0 or f ′(c) is undefined, then c is called a critical
 value of f.
    To find intervals of increase and decrease, find all points of discontinuity and
                      critical values. Then organize a sign chart.
              Concavity and Points of Inflection
If f ′′ < 0 on (a, b), then f ′ is decreasing and f is concave down on (a, b).
                                       Chain Rule
                                                  𝑑
                   Version 1 (most used):         𝑑𝑥
                                                     [𝑓(𝑔(𝑥))]    = 𝑓′(𝑔(𝑥)) ∙ 𝑔′(𝑥)
                                                      𝑑𝑦     𝑑𝑦 𝑑𝑢
                                      Version 2:      𝑑𝑥
                                                           = 𝑑𝑢 ∙ 𝑑𝑥
NOTE: The chain rule must often be used to take the derivatives in the product & quotient rule.
Derivative Rules (Version 1 – Don’t Glue Yet!)
 Note: These include the chain rule:
                                               E
                                    Motion
Velocity
    Velocity is the derivative of position: v(t) = s′(t)
    When velocity > 0, object is moving in a positive direction (right or up for linear
     motion)
    When velocity < 0, object is moving in a negative direction (left or down for linear
     motion)
    When velocity equals 0, the object is at rest.
Acceleration
    Acceleration is the derivative of velocity and the 2nd derivative of position:
     a(t) = v′(t) = s′′(t)
    When acceleration > 0, the velocity of the object is increasing.
    When acceleration < 0, the velocity of the object is decreasing.
         𝑑 𝑢
            (𝑎 ) = 𝑢′ ∙ 𝑎𝑢 ∙ ln 𝑎
         𝑑𝑥
     Logarithmic:
         𝑑           𝑢′
            (ln 𝑢) =
         𝑑𝑥          𝑢
         𝑑                 𝑢′
            (log 𝑎 𝑢) =
         𝑑𝑥             𝑢 ∙ ln 𝑎
Extreme Value Theorem (EVT) & Absolute Extrema
  Finding Both the Absolute Maximum & the Absolute Minimum on a Closed Interval
    1. Find the critical values of f on the interval (a, b).
    2. Evaluate f at the critical values AND the endpoints x = a and x = b.
    3. The smallest value is the absolute minimum. The largest value is the absolute
       maximum.
                             𝑓(𝑏) − 𝑓(𝑎)
                 𝑓 ′ (𝑐) =
                                𝑏−𝑎
  Rolle’s Theorem
  If f(x) is continuous on [a, b], differentiable on (a, b), AND f(a) = f(b), then there
  exists an x =c in the interval (a, b) such that:
                             𝑓(𝑏) − 𝑓(𝑎)
                 𝑓 ′ (𝑐) =               =0
                                𝑏−𝑎
      NOTE: f(a) & f(b) don’t have to be 0. They just have to be the same. But when
           Rolle’s applies, the derivative is set equal to 0.
                                      L’Hôpital’s Rule
          𝑓(𝑥)                                   𝑓(𝑥)         𝑓′(𝑥)
  If lim 𝑔(𝑥) is indeterminate, then lim 𝑔(𝑥) = lim 𝑔′(𝑥) .
    𝑥→𝑎                                    𝑥→𝑎          𝑥→𝑎
NOTE: Students often make mistakes when the term –xy is part of the equation.
     Remember, you need to use the product rule for this with –x as one part and y
     as the other part. Many students lose the negative sign when doing the
     product rule because they don’t think about it being “attached” to the x!
NOTE: The derivative of an implicit equation usually includes both x and y. If you are
     asked to find the derivative at a particular x-value, you must first substitute
     that x-value into the original equation to find the corresponding y-value. Then
     you will substitute the x- and y-value in simultaneously to find the derivative
     at that particular ordered pair.
                              Derivative Rules
 Note: These include the chain rule:
 Example: To find 𝑓 −1 (2), you need to find where the function f(x) = 2. Remember:
          The input of an inverse function 𝑓 −1 is the output of the function f.
                           Related Rates
NOTE: Look to see if any quantities are constant in the situation. If so, you can
     substitute them if before taking the derivative, making your derivative
     much easier. However, be careful not to substitute any values that are only
     equal to that measurement or rate at a specific instant in time. You must
     wait to substitute these values until after you have taken the derivative.
NOTE: Sometimes you have to use a second equation to relate two quantities in
     order to eliminate variables in your main equation. Realizing you have to do
     this often saves time and makes your derivative and work less messy.
              Linearization & Differentials
Linearization Equation
Used to estimate the value of a function that would be difficult to find without a
calculator.
       𝐿(𝑥) = 𝑓 ′ (𝑎)(𝑥 − 𝑎) + 𝑓(𝑎) where a is the center of the approximation
NOTE: This is just the tangent line at x = a in a slightly different form.
Differentials
Often used to find how one variable changes with respect to the other. Also used
to estimate the value of a function as it is the same as the linearization equation in
a slightly different format.
       𝑓(𝑥 + Δ𝑥) ≈ 𝑓 ′ (𝑥)𝑑𝑥 + 𝑓(𝑥)
NOTE: This is also just the tangent line at x = a in a slightly different form.
                          Curve Sketching
      o Right endpoint
            f ʹ(x) negative before ⇒ f(x) decreasing ⇒ Right is relative min
            f ʹ(x) positive before ⇒ f(x) increasing ⇒ Right is relative max
Trapezoidal Rule
For equal width subintervals, the area under the curve can be approximated by
the Trapezoidal Rule:
                  Δ𝑥
         𝐴𝑟𝑒𝑎 ≈      (𝑓(𝑥0 ) + 2𝑓(𝑥1 ) + 2𝑓(𝑥2 ) + ⋯ + 2𝑓(𝑥𝑛−1 ) + 𝑓(𝑥𝑛 ))
                  2
NOTE: If subintervals are not equal width, you must find the areas of individual
                                                    1
     trapezoids and add their areas together. 𝐴 = ℎ(𝑏1 − 𝑏2 )
                                                    2
                         Integration Formulas
                                   Trig:
∫ 𝑘 𝑑𝑥 = 𝑘𝑥 + 𝐶 , 𝑘 is a consant
                                      ∫ sin 𝑥 𝑑𝑥 = − cos 𝑥 + 𝐶
   𝑛
         𝑥 𝑛+1
∫ 𝑥 𝑑𝑥 =       + 𝐶, if 𝑛 ≠ −1
         𝑛+1
                                      ∫ cos 𝑥 𝑑𝑥 = sin 𝑥 + 𝐶
∫ 𝑒 𝑥 𝑑𝑥 = 𝑒 𝑥 + 𝐶
                                      ∫ sec 2 𝑥 𝑑𝑥 = tan 𝑥 + 𝐶
 1
∫ 𝑑𝑥 = ln|𝑥| + 𝐶
 𝑥
                                      ∫ csc 2 𝑥 𝑑𝑥 = −cot 𝑥 + 𝐶
                𝑎𝑥
∫ 𝑎 𝑥 𝑑𝑥 =          +𝐶
               ln 𝑎
                                      ∫ sec 𝑥 tan 𝑥 𝑑𝑥 = sec 𝑥 + 𝐶
    1
∫        𝑑𝑥 = arctan 𝑥 + 𝐶
  1 + 𝑥2
                                      ∫ csc 𝑥 cot 𝑥 𝑑𝑥 = −csc 𝑥 + 𝐶
       1
∫              𝑑𝑥 = arcsin 𝑥 + 𝐶
    √1 − 𝑥 2
              Properties of Definite Integrals
                                              𝑏
   Integral Evaluation Theorem: ∫𝑎 𝑓(𝑥)𝑑𝑥 = 𝐹(𝑏) − 𝐹(𝑎)
                                where F is an antiderivative of f.
                                      𝑎                𝑏
   Order of Integration Rule: ∫𝑏 𝑓(𝑥)𝑑𝑥 = − ∫𝑎 𝑓(𝑥)𝑑𝑥
                 𝑎
   Zero Rule: ∫𝑎 𝑓(𝑥)𝑑𝑥 = 0
                     𝑏                𝑏
   Scalar Rule: ∫𝑎 𝑘𝑓(𝑥)𝑑𝑥 = 𝑘 ∫𝑎 𝑓(𝑥)𝑑𝑥
                                  𝑏                        𝑏           𝑏
   Sum & Difference Rule: ∫𝑎 (𝑓(𝑥) + 𝑔(𝑥)) 𝑑𝑥 = ∫𝑎 𝑓(𝑥)𝑑𝑥 + ∫𝑎 𝑔(𝑥)𝑑𝑥
                         𝑏                𝑐        𝑐
   Additivity Rule: ∫𝑎 𝑓(𝑥)𝑑𝑥 + ∫𝑏 𝑓(𝑥)𝑑𝑥 = ∫𝑎 𝑓(𝑥)𝑑𝑥
   NOTE: Another way to write the MVT for Integrals is shown below. This is the
   result of taking the formula above and multiplying by (b – a)
                              𝑏
            𝑓(𝑐)(𝑏 − 𝑎) = ∫ 𝑓(𝑥)𝑑𝑥
                             𝑎
           Fundamental Theorem of Calculus
If f is continuous on an open interval I containing a, then, for every x in the
interval,
                𝑥
           𝑑
              [∫ 𝑓(𝑡)𝑑𝑡] = 𝑓(𝑥)
           𝑑𝑥 𝑎
NOTES:
    The bottom limit of integration must be a constant.
    The upper limit of integration must be a function.
When the upper limit is not just x, but function of x (like x2):
             𝑢
         𝑑
           [∫ 𝑓(𝑡)𝑑𝑡] = 𝑢′𝑓(𝑢)
         𝑑𝑥 𝑎
         Where u is a function of x.
 NOTE: When finding total distance by hand, you must find where v(t) changes
      sign. You must set up multiple integrals if v(t) changes sign, then add the
      absolute values of each integral.
 NOTE: When finding total distance on a calculator, you can just type in the
      integral above with the absolute value bars around the v(t) function.
Velocity
        Velocity is the derivative of position: v(t) = s′(t)
        When velocity > 0, object is moving in a positive direction (right or up for
         linear motion)
        When velocity < 0, object is moving in a negative direction (left or down for
         linear motion)
        When velocity equals 0, the object is at rest.
Acceleration
        Acceleration is the derivative of velocity and the 2nd derivative of position:
         a(t) = v′(t) = s′′(t)
        When acceleration > 0, the velocity of the object is increasing.
        When acceleration < 0, the velocity of the object is decreasing.
A net change problem is when you are given a rate and are asked to find things
about the rate and the total amount. This is related to motion problems about
displacement, position, and distance. However, the rate given is not velocity but is
about a situation other than motion.
     Where c & d are y-values and f(y) is to the right of g(y). NOTE: Functions are
     x = something in terms of y.
                    Volume: Disk Method
Disk Method:
   • We use the disk method when the area to be revolved is touching the axis of
     revolution.
   • The representative rectangle (strip) must be perpendicular to the axis of
     revolution.
   • Disks are just flat cylinders. Therefore we are integrating the volume of a
     cylinder where 𝜋𝑟 2 is the area of the base and dx (or dy)is the very small
     height of the cylinder.
   • When revolving around another horizontal axis y = k, the radius is not just
     the function given. You must adjust the radius by subtracting the value of k.
     The formula becomes:
                       𝑏
            𝑉 = 𝜋 ∫ [𝑓(𝑥) − 𝑘]2 𝑑𝑥
                   𝑎
• VERTICAL STRIPS!
   • When revolving around another vertical axis x = k, the radius is not just the
     function given. You must adjust the radius by subtracting the value of k. The
     formula becomes:
                       𝑑
            𝑉 = 𝜋 ∫ [𝑓(𝑦) − 𝑘]2 𝑑𝑦
                   𝑐
   • HORIZONTAL STRIPS!
                 Volume: Washer Method
Washer Method:
   • We use the disk method when the area to be revolved is not touching the
     axis of revolution.
   • The representative rectangle (strip) must be perpendicular to the axis of
     revolution.
   • Washers are the outer flat cylinders minus the inner flat cylinder. Therefore
     we are integrating the volume of a cylinder where 𝜋𝑅 2 is the area of the
     base of the outer cylinder, 𝜋𝑟 2 is the area of the base of the inner cylinder
     and dx (or dy)is the very small height of the cylinder.
   • When revolving around another horizontal axis y = k, the radius is not just
     the function value. You must adjust each radius by subtracting the value of
     k. The formula becomes:
                       𝑏
            𝑉 = 𝜋 ∫ ([𝑅(𝑥) − 𝑘]2 − [𝑟(𝑥) − 𝑘]2 )𝑑𝑥
                   𝑎
• VERTICAL STRIPS!
   • When revolving around another vertical axis y = k, the radius is not just the
     function value. You must adjust each radius by subtracting the value of k.
     The formula becomes:
                       𝑑
            𝑉 = 𝜋 ∫ ([𝑅(𝑦) − 𝑘]2 − [𝑟(𝑦) − 𝑘]2 )𝑑𝑦
                   𝑐
   • HORIZONTAL STRIPS!
Volume: Cross Sections & Area Formulas to Know
      NOTE: The area of the cross section formula that becomes the integrand will
           typically contain the function given. However, it is not always just the
           function. Draw a picture to help you figure out the area formula in
           terms of x (or y).
   2. Find 𝑥𝑘 = Δ𝑥𝑘 + 𝑎
   3. Substitute into limit notation above.
Use long division before integrating when ALL of the following are present:
NOTE: Once you have completed the square, the resulting integrand will have an
     antiderivative that is an inverse trig function.
Integration by Parts
Indefinite: ∫ 𝑢 𝑑𝑣 = 𝑢𝑣 − ∫ 𝑣 𝑑𝑢
            𝑏                 𝑏
Definite: ∫𝑎 𝑢 𝑑𝑣 = [𝑢𝑣]𝑏𝑎 − ∫𝑎 𝑣 𝑑𝑢
Tabular Integration by Parts can be used if and only if one function differentiates
to zero eventually, and the other continually integrates.
                       L’Hôpital’s Rule (Part 2)
        𝑓(𝑥)                                𝑓(𝑥)          𝑓′(𝑥)
If lim 𝑔(𝑥) is indeterminate, then lim 𝑔(𝑥) = lim 𝑔′(𝑥) .
  𝑥→𝑎                               𝑥→𝑎             𝑥→𝑎
                               0        ∞
   NOTE: The limit must be     0
                                   or   ∞
                                            to use L’Hôpital’s Rule.
   • For 1 , 0 , and ∞0 , take the ln of both sides to bring down the exponent. Then
               ∞   0
follow the steps for ∞ ∙ 0. Don’t forget to exponentiate to reverse the ln!
3. If f is continuous on the interval [a, b], except for some c in (a, b) at which f has an
   infinite discontinuity, then
           b                            c                          b
       a
               f ( x)dx = lim−
                            c →c    
                                    a
                                            f ( x)dx + lim+
                                                           c →c    f ( x)dx
                                                                  c
                                   Euler’s Method
• Euler’s Method is used to estimate the value of the function from a differential
  equation, particularly when the variables cannot be separated to find the particular
  solution.
• The accuracy of the estimation increases as the distance between the initial
  condition x-value and the desired x-value decreases.
                                     𝑏       𝑑𝑦             2              𝑑      𝑑𝑥2
Arc Length (Regular Functions): 𝐿 = ∫𝑎 √1 + (𝑑𝑥 ) 𝑑𝑥            or   𝐿 = ∫𝑐 √1 + (𝑑𝑦) 𝑑𝑦
                                   𝑀                                                 𝑀−𝑃0
Logistic Growth Model: 𝑃 = 1+𝐴𝑒 −𝑘𝑡            where M = carrying capacity and 𝐴 =    𝑃0
                                        1
Fastest Growth Occurs when 𝑃 = 2 𝑀
lim 𝑃(𝑡) = 𝑀
𝑡→∞
                       Parametric Equations
Position:
   • Horizontal position = x(t)
   • Vertical position = y(t)
    𝑑𝑦
𝑑𝑦 𝑑𝑡
  =
𝑑𝑥 𝑑𝑥
    𝑑𝑡
                   𝑑𝑦
𝑑2 𝑦 derivative of 𝑑𝑥
     =
𝑑𝑥 2       𝑑𝑥
            𝑑𝑡
                                                    𝑏   𝑑𝑥    𝑑𝑦   2        2
Length of Curve (aka distance object travels): 𝐿 = ∫𝑎 √( ) + ( ) 𝑑𝑡
                                                              𝑑𝑡       𝑑𝑡
Object is moving:
                  𝑑𝑥
   • Left when 𝑑𝑡 < 0
                       𝑑𝑥
    •   Right when 𝑑𝑡 > 0
                       𝑑𝑦
    •   Down when           <0
                       𝑑𝑡
                  𝑑𝑦
    •   Up when 𝑑𝑡 > 0
                            𝑑𝑥   𝑑𝑦
Object is at rest when 𝑑𝑡 and 𝑑𝑡 both equal zero at the same value of t.
                                 𝑑𝑥
Tangent line is vertical when 𝑑𝑡 is zero. Must often find the position (x, y) for the
solution for t.
                                      𝑑𝑦                 𝑑𝑥
Tangent line is horizontal when 𝑑𝑡 is zero (as long as 𝑑𝑡 is not also 0). Must often
find the position (x, y) for the solution for t.
                                             Vectors
                                𝑣(𝑎)
        Direction (t = a):     |𝑣(𝑎)|
                                        (Result is a vector)
Object is moving:
                  𝑑𝑥
   • Left when 𝑑𝑡 < 0
                         𝑑𝑥
    •     Right when          >0
                         𝑑𝑡
                         𝑑𝑦
    •     Down when 𝑑𝑡 < 0
                    𝑑𝑦
    •     Up when 𝑑𝑡 > 0
                              𝑑𝑥        𝑑𝑦
Object is at rest when 𝑑𝑡 and 𝑑𝑡 both equal zero at the same value of t.
                                    𝑏   𝑑𝑥       𝑑𝑦   2        2
Distance traveled by particle: 𝐿 = ∫𝑎 √( 𝑑𝑡 ) + ( 𝑑𝑡 ) 𝑑𝑡
                            Polar Equations
     𝑑𝑦                     𝑑𝑟
 𝑑𝑦 𝑑𝜃 𝑟 ′ sin 𝜃 + 𝑟 cos 𝜃 𝑑𝜃 sin 𝜃 + 𝑟 cos 𝜃
   =    =                 =
 𝑑𝑥 𝑑𝑥 𝑟 ′ cos 𝜃 − 𝑟 sin 𝜃 𝑑𝑟 cos 𝜃 − 𝑟 sin 𝜃
     𝑑𝜃                     𝑑𝜃
                              1   𝑏
 Area inside polar curve: 𝐴 = 2 ∫𝑎 𝑟 2 𝑑𝜃 (may have to find bounds for one period)
                                      1       𝑏
 Area between polar curves: 𝐴 = 2 ∫𝑎 (𝑅 2 − 𝑟 2 ) 𝑑𝜃 (may have to find intersections)
                        𝑏
 Polar arc length: 𝐿 = ∫𝑎 √(𝑟)2 + (𝑟′)2 𝑑𝜃
                                    𝑏       𝑑𝑦    2               𝑑      𝑑𝑥        2
Arc Length for functions of x: 𝐿 = ∫𝑎 √1 + (𝑑𝑥 ) 𝑑𝑥    or   𝐿 = ∫𝑐 √1 + (𝑑𝑦) 𝑑𝑦
                                                                   𝑏   𝑑𝑥    𝑑𝑦2            2
Arc Length for parametric (equivalent to distance travelled): 𝐿 = ∫𝑎 √( ) + ( ) 𝑑𝑡
                                                                          𝑑𝑡           𝑑𝑡
                                  𝑏                     𝑏         𝑑𝑟  2
Arc Length for polar curves: 𝐿 = ∫𝑎 √(𝑟)2 + (𝑟′)2 𝑑𝜃 = ∫𝑎 √𝑟 2 + (𝑑𝜃) 𝑑𝜃