CH 11 Equations
CH 11 Equations
PRACTICE SHEET-1
1. A train started from a station with a certain
number of passengers. At the first halt, 7. Let there be three simultaneous linear
1/3rd of its passengers got down and 120 equations in two unknowns, which are non-
passengers got in. At the second halt, half of parallel and non-collinear them. What can
the passengers got down and 100 persons be the number of solutions (if they do exist)?
got in. Then, the train left for its destination (a) One or infinite (b) Only one
with 240 passengers. How many passengers (c) Exactly two (d) exactly three
were there in the train when it started?
(a) 540 (b) 480 8. If 1 is added to the denominator of a
(c) 360 (d) 240 fraction, it becomes 1/2 and if 1 is added to
the numerator, the fraction becomes 1. What
2. A person bought a certain number of books is the fraction?
for Rs 80. If he had bought 4 more books for (a) 5/9 (b) 2/3
the same sum, each book would have cost (c) 4/7 (d) 10/11
Rs 1 less. What is the price of each book?
(a) Rs 10 (b) Rs 8 2 3 9 and 4 9 21 , where x ≠ 0
9. If
(c) Rs 5 (d) Rs 4 x y xy x y xy
and y ≠ 0, then what is the value of x + y?
3. A person bought 5 tickets from a station P to
(a) 2 (b) 3
a station Q and 10 tickets from the station P
(c) 4 (d) 8
to a station R. He paid Rs 350. If the sum of
a ticket from P to Q and a ticket from P to R
10. The sum of two numbers is 80. If the larger
is Rs 42, then what is the fare from P to Q?
number exceeds four times the smaller by 5,
(a) Rs 12 (b) Rs 14
what is the smaller number?
(c) Rs 16 (d) Rs 18
(a) 5 (b) 15
(c) 20 (d) 25
4. Pooja started her job with certain monthly
salary and gets a fixed increment every year.
11. If 2a + 3b = 17 and 2a+2 − 3b+1 = 5, then,
If her salary was Rs 4200 after 3 years and `
(a) a = 2, b = 3 (b) a = -2, b = 3
6800 after 8 years of service, then what are
(c) a = 2, b = –3 (d) a = 3, b = 2
her initial salary and the annual increment,
respectively?
2 x 3 y 1 x 4 y 8 4 x 7 y 2 then what is
(a) Rs 2640, Rs 320 (b) Rs 2460, Rs 320 12. If
2 3 5
(c) Rs 2460, Rs 520 (d) Rs 2640, Rs 520
(x + y) equal to?
(a) 3 (b) 2
5. A number consists of two digits, whose sum
(c) 0 (d) –2
is 10. If 18 is subtracted from the number,
digits of the number are reversed. What is
13. Sum of two numbers is 21 and their
the product?
difference is 11, then the greatest number is
(a) 15 (b) 18
(a) 5 (b) 16
(c) 24 (d) 32
(c) 9 (d) 10
6. A railway ticket for a child costs half the full
14. The area of a rectangle remains the same if
fare but the reservation charge is the same
the length is increased by 7 m and the
on half tickets as much as on full ticket. One
breadth is decreased by 3 m. The area
reserved first class ticket for a journey
remains unaffected if the length is decreased
between two stations is Rs 362, one full and
by 7 m and the breadth is increased by 5 m ,
one half reserved first class tickets cost Rs
then area of rectangle is
554. What is the reservation charge?
(a) 280 m2 (b) 320 m2
(a) Rs 18 (b) Rs 22
(c) 420 m 2 (d) 400 m2
(c) Rs 38 (d) Rs 46
ANSWER KEY
1. (d) 2. (c) 3. (b) 4. (d) 5. (c) 6. (b) 7. (b) 8. (b) 9. (c) 10. (b)
11. (d) 12. (d) 13. (b) 14. (c) 15. (c) 16. (c) 17. (b) 18. (b) 19. (a) 20. (b)
21. (a) 22. (b) 23. (d) 24. (a) 25. (c) 26. (d) 27. (b) 28. (a) 29. (b) 30. (c)
PRACTICE SHEET-2
1. A men has some hens and cows. If the (1) 6 (2) 10
number of heads be 48 and the number of (3) 12 (4) 14
feet equals 140, then the number of hens 5. A fraction becomes 1 when 1 is subtracted
will be 3
(1) 23 (2) 22 from both the numerator and the
(3) 24 (4) 26 1
denominator. The same fraction becomes
2. Slope of the line 2x − y + 4 = 0 is 2
(1) 2 (2) 1 when 1 is added to both the numerator and
the denominator. The sum of numerator and
(3) 0 (4) 1/2
denominator of the fraction is
(1) 10 (2) 18
3. A number consists of two digits. If the (3) 7 (4) 16
number formed by interchanging the digits
is added to the original number, the 6. If 1 is added to both the numerator and the
resulting number (i.e. the sum) must be 1 . If 2
divisible by denominator of a fraction, it becomes
4
(1) 11 (2)9
is added to both the numerator and the
(3) 5 (4)3
denominator of that fraction, it becomes 1 .
3
4. If 1 is added to the denominator of a fraction The sum of numerator and denominator of
it becomes 1 . If 1 is added to the numerator the fraction is:
2 (1) 8 (2) 13
it becomes 1. The product of numerator and (3) 22 (4) 27
denominator of the fraction is
ANSWER KEY
1. (4) 2. (1) 3. (1) 4. (1) 5. (1) 6. (1) 7. (4) 8. (2) 9. (3) 10. (3)
11. (3) 12. (2) 13. (2) 14. (4) 15. (2) 16. (4) 17. (2) 18. (2) 19. (4) 20. (4)
21. (2) 22. (3) 23. (3) 24. (3) 25. (4) 26. (2) 27. (1) 28. (4) 29. (2) 30. (2)
PRACTICE SHEET-3
1. Every quadratic equation ax2 + bx + c = 0, 1b q 1 b q
where a, b, c R, a ≠ 0 has: (c) (d)
2p a 2 a a
(a) Exactly one real root
(b) At least one real root
3. If and are the roots the equation ax2 + bx
(c) At least two real roots
(d) At most two real roots + c = 0, where a ≠ 0, then (a + b) (a + b) is
equal to:
(a) ab (b) bc
2. If , are roots of ax2 + bx + c = 0 and + h,
(c) ca (d) abc
+ h are the roots of px2 + qx + r = 0, then
what is h equal to?
4. The roots of the equation 2a2 x2 2abx + b2
1b q 1 b q = 0, when a < 0 and b > 0 are:
(a) (b)
2a p 2 a p (a) Sometimes complex (b) Always irrational
ANSWER KEY
1. (c) 2. (a) 3. (c) 4. (c) 5. (d) 6. (c) 7. (d) 8. (b) 9. (c) 10. (a)
11. (d) 12. (a) 13. (a) 14. (a) 15. (a) 16. (a) 17. (d) 18. (c) 19. (d) 20. (c)
21. (a) 22. (a) 23. (d) 24. (c) 25. (b) 26. (a) 27. (d) 28. (c) 29. (c) 30. (c)
PRACTICE SHEET-4
1. If the product of the roots of x 2 – 3kx + 2k2 – 0 may be found by solving which one of the
1 = 0 is 7 for a fixed k, then what is the following equations?
nature of roots? (a) y2 + 14y – 7 = 0 (b) y2 + 8y + 1 = 0
(a) Integral and positive (c) y2 + 10y – 7 = 0 (d) y2 – 8y + 7 = 0
(b) Integral and negative
(c) Irrational 4. If a polynomial equation has rational co-
(d) Rational but not integral efficient and has exactly three real roots,
then what is the degree of the polynomial?
2. Which one of the following is the quadratic (a) Equal to 3
equation whose roots are reciprocal to the (b) Greater than or equal to 3
roots of the quadratic equation 2x2 – 3x – 4 = (c) Strictly greater than 3
0? (d) Less than 3
(a) 3x2 – 2x – 4 = 0 (b) 4x2 + 3x – 2 = 0
(c) 3x – 4x – 2 = 0
2 (d) 4x2 – 2x – 3 = 0 5. If α and β are the roots of ax2 + bx + c = 0,
2
then what is the value of 1 1
3. The value of y which will satisfy the 2
2
equations 2x2 + 6x + 5y + 1 and 2x + y + 3 =
6. Which one of the following is one of the two 15. r is a non-zero real number such that r75 >
consecutive positive integers, the sum of r90. This is possible only when
whose squares is 761? (a) –1 < r < 0 (b) 0 < r < 1
(a) 15 (b) 20 (c) 1 < r (d) –1 < r < 1
(c) 24 (d) 25
16. When the roots of the quadratic equation ax 2
7. If 3x + 27(3–x) = 12, then what is the value of + bx + c = 0 are negative of reciprocals of
x? each other, then which one of the following
(a) Only 1 (b) Only 2 is correct?
(c) 1 or 2 (d) 0 or 1 (a) b = 0 (b) c = 0
(c) a = c (d) a = –c
8. What is the magnitude of difference of the
roots of x2 – ax + b = 0? 17. What are the roots of the equation log10(x2 –
(a) a 4b
2
(b) b 4a
2 6x + 45) = 2?
(a) 9, –5 (b) –9, 5
(c) 2 a 2 4b (d) b 2 4ab (c) 11, –5 (d) –11, 5
9. If a + b = 2m2, b + c = 6m, a + c = 2, where 18. The sum of the roots of the equation
m is a real number and a ≤ b ≤ c, then which 1 1 1
one of the following is correct? is zero. What is the product
(a) 0 ≤ m ≤ 1/2 (b) −1 ≤ m ≤ 0
x a x b c
of the roots of the equation?
(c) 1/3 ≤ m 1 d) 1 < m ≤ 2
( a b) ( a b)
(a) (b)
10. Students of a class are made to stand in 2 2
rows. If one student is extra in a row, there (a b )
2 2
(a b 2 )
2
ANSWER KEY
1. (c) 2. (b) 3. (c) 4. (a) 5. (a) 6. (b) 7. (c) 8. (a) 9. (c) 10. (c)
11. (d) 12. (d) 13. (c) 14. (c) 15. (b) 16. (d) 17. (c) 18. (c) 19. (b) 20. (a)
21. (c) 22. (b) 23. (a) 24. (c) 25. (a) 26. (d) 27. (b) 28. (d) 29. (d) 30. (d)
22. If m and n (m > n) are the roots of the 28. For which value of k does the pair of
equation 7(x + 2a)2 + 3a2 = 5a (7x + 23a), equations x2 – y2 = 0 and (x – k)2 + y2 = 1
where a > 0, then what is 3m–n equal to? yield a unique positive solution of x?
[CDS 2014 (2)] [CDS 2015 (1)]
(a) 12a (b) 14a (a) 2 (b) 0
(c) 15a (d) 18a (c) 2 (d) – 2
23. If one the roots of the equation px2 + qx + r = 29. The sign of the quadratic polynomial ax2 +
0 is three times the other, then which one of bx + c is always positive if:
the following relations is correct? [CDS 2015 (1)]
[CDS 2014 (2)] (a) a is positive and b2–4ac 0
(a) 3q2 = 16 pr (b) a2 = 24 pr (b) a is positive and b2–4ac 0
(c) p = q + r (d) p + q + r = 1 (c) a can be any real number and b2–4ac 0
(d) a can be any real number and b2–4ac 0
24. If m and n are the roots of the equation x2 +
30. If k = x – y + 2z where –2 ≤ x ≤ 1, –1≤ y ≤ 2
ax + b = 0 and m2, n2 are the roots of the and 3 ≤ z ≤ 6, then which one of the
equation x2 – cx + d = 0, then which of the following is correct?
following is/are correct? [CDS 2015 (2)]
1. 2b – a2 = c (a) 0 ≤ k ≤ 9 (b) 5 ≤ k ≤ 11
2. b2 = d (c) 2 ≤ k ≤ 14 (d) 2 ≤ k ≤ 11
Select the correct answer using the codes
31. The number of pairs (x, y) where x, y are
given below: integers satisfying the equation 21x+48y=5
[CDS 2014 (2)] is:
(a) Only 1 (b) Only 2 [CDS 2015 (2)]
(c) Both 1 and 2 (d) Neither 1 nor 2 (a) Zero (b) One
(c) Two (d) Infinity
25. If (x+k) is the common factor of x2 + ax + b
32. Let x and y be positive integers such that x
and x2 + cx + d of and then what is k equal
is prime and y is composite. Which of the
to? following statements are correct?
[CDS 2014 (2)] 1. (y–x) can be an even integer
(a) (d–b)/(c–a) (b) (d–b)/(a–c) 2. xy can be an even integer
(c) (d+b)/(c+a) (d) (d–b)/(c+a) 3. 0.5 (x+ y) can be an even integer
Select the correct answer using the code
26. If the equation x + 2(1+k) x+k = 0 has
2 2 given below:
[CDS 2015 (2)]
equal roots, then what is the value of k?
(a) 1 and 2 only (b) 2 and 3 only
[CDS 2014 (2)] (c) 1 and 3 only (d) 1, 2 and 3
(a) 1/2 (b) –1/2
(c) 1 (d) –1 33. If the roots of the quadratic equations x2 – 4
– log10 N = 0 are all real, then the minimum
27. Consider the following statements: value of N is:
[CDS 2015 (2)]
1.The equation 1990x – 173y = 11 has no
1 1
solution in integers for x and y. (a) (b)
2.The equation 3x –12y = 7 has no solution 100 1000
in integers for x and y.
10000
3
..
2 2x 6y=21
expressions (6 + 5x – x2) and (y – 6 – y2) for 1
any real values of x and y is: 0 1 2
[CDS 2015 (2)] 3 4
The linear in equations, for which the
(a) 16 (b) 17
shaded area in the figure given above is the
(c) 18 (d) 19
solution set, are:
[CDS 2016 (1)]
35. What is 4 4 4 4 ............... equal to? (a) 2x+6y ≤ 21, 5x – 2y ≤ 10
(b) 2x+6y ≤ 21, 5x – 2y 10
[CDS 2015 (2)] (c) 2x+6y 21, 5x – 2y ≤ 10
13 1 (d) 2x+6y 21, 5x – 2y 10
(a) 3 (b)
2
41. If a and b are negative real numbers and c is
13 1
(c) (d) 0 a positive real number, then which of the
2 following is/are correct?
4
1. a – b < a – c
36. A tin of oil was full. When 6 bottles of oil a b
5
were taken out from this tin and 4 bottles of 2. If a < b then
3
c c
oil were poured into it, it was full. Oil of 1 1
4
how many bottles can the tin contain? (All 3.
b c
bottles are of equal volume)
Select the correct answer using the code
[CDS 2015 (2)]
given below:
(a) 35 (b) 40
[CDS 2016 (1)]
(c) 45 (d) 50
(a) 1 (b) 2 only
(c) 3 only (d) 2 and 3
37. If the equations x2 – px + q = 0 and x2 + qx –
p = 0 have a common root, then which one 42. If the roots of the equation lx2 + mx + m = 0
of the following is correct? are in the ratio p : q, then:
[CDS 2016 (1)] p q m
(a) p–q=0 (b) p+q–2=0 is equal to:
q p l
(c) p+q–1=0 (d) p–q–1=0
[CDS 2016 (1)]
38. The value of k, for which the system of (a) 0 (b) 1
equation 3x – ky – 20 = 0 and 6x –10y + 40 = (c) 2 (d) 3
0 has no solution, is:
[CDS 2016 (1)] 43. If 3x 2 7x 30 2x 2 7x 5 x 5 has
and as its roots, then the value of is:
(a) 10 (b) 6 [CDS 2016 (1)]
(c) 5 (d) 3
(a) –15 (b) –5
39. There are three brothers. The sums of ages (c) 0 (d) 5
of two of them at a time are 4 years, 6 years
and 8 years. The age difference between the 44. Let p and q be non-zero integers. Consider
eldest and the youngest is: the polynomial A(x) = x2 + px + q.
[CDS 2016 (1)] It is given that (x – m) and (x –km) are linear
(a) 3 years (b) 4 years factors of A (x), where m is a non-zero
(c) 5 years (d) 6 years integer and k is a positive integer, k 2.
Which one of the following is correct?
40. [CDS 2016 (1)]
(a) (k +1)2 p2 = kg (b) (k +1)2 q = kp2
(c) k2 q =(k +1) p2 (d) k2p2 =(k +1)2q
page, the number of pages would have to be – kx + 2 = 0 have real and distinct
increased by 10 to give the same writing solutions?
space. What is the value of n? [CDS 2021 (2)]
[CDS 2020 (2)] (a) –2√2 < k < 2√2
(a) 18 (b) 21 (b) k <–2√2 only
(c) 24 (d) 30 (c) k > 2√2 only
(d) k < –2√2 or k > 2√2
105. If the equation 4x2 – 2kx + 3k = 0 has equal
roots, then what are the values of k? 112. 5 pencils, 6 notebooks and 7 erasers Cost
[CDS 2021 (1)] Rs250; whereas 6 pencils, 4 notebooks and
2 erasers cost Rs180. What is the cost of 2
(a) 4, 12 (b) 4, 8 notebooks and 4 erasers?
(c) 0, 12 (d) 0, 8 [CDS 2021 (2)]
132. Consider the following statements in 139. Question: What are the unique values of a,
respect of the polynomial a(b – c) (x – b) (x – b and c if 2 is a root of the equation ax 2 +
c) + b (c – a) (x – c) (x – a) + c(a – b)(x – a) (x bx + c = 0?
– b): Statement I: Ratio of c to a is 1
1.the coefficient of x2 is 0 Statement II: Ratio of b to a is (–5/2)
2.The coefficient of x is (a – b) (b – c) (c – a) [CDS – 2023 (1)]
Which of the statements given above is/are (a) Choose this option if the question can be
correct? answered by one of the statements alone
[CDS – 2023 (1)] but not by the other.
(a) 1 only (b) 2 only (b) Choose this option if the question can be
(c) both 1 and 2 (d) neither 1 nor 2 answered by either statement alone.
(c) Choose this option if the question can be
133. For what values of m, is mx2 + mx + 8x + 9 answered by using both the statements
a perfect square? together, but cannot be answered by using
[CDS – 2023 (1)] either statement alone
(a) 1, 4 (b) 4, 9 (d)Choose this option if the question cannot
(c) 9, 16 (d) 4, 16 be answered even by using both statements
together
150. How many real roots does the equation Consider the following for the next two
x 9 = x–3 have? (02) items that follow:
[CDS-2023 (2)] A quadratic equation is given by (a + b +
(a) only one (b) only two c)x2 – (2a + 2b)x + (a + b – c) = 0; where a, b
(c) only three (d) none and c are real and distinct.
151. If 3x–1 + 33–x = 6, then what is 2x–1 + 23–x 156. What are the roots of the equation?
equal to? [CDS-2023 (2)]
[CDS-2023 (2)] (a) 1, a b c
(b) 1, a b c
(a) 4 (b) 3 a b c a b c
(c) 2 (d) 1 (c) –1, a c c
(d) –1, a b c
a b c a b c
Consider the following for the next two
(02) items that follow: 157. Consider the following statements:
1.One of the roots of the equation is always
Let x a x b x a x b ; m, a, b > 0. less than 1 if a, b and c are all positive
x ma x mb x ma x mb
2.One of two roots of the equation is always
2 negative if a, b and c are all negative.
152. What is 2x ab equal to? Which of the statements given above is/are
x m 2ab
correct?
[CDS-2023 (2)] [CDS-2023 (2)]
(a) – 12 (b) 12 (a) 1 only (b) 2 only
m m
(c) both 1 and 2 (d) neither 1 nor 2
2 1
(c) (d)
m m
158. If the equation x cos = x2 + p has a real
153. What is x equal to?
solution for every , where 0 , then
[CDS-2023 (2)] 4
(a) ± mab (b) ± ab which one of the following is correct?
[CDS-2024 (1)]
(c) ± 2mab (d) ± 2ab (a) p = 1/8 (b) p 1/8
(c) p 1/8 (d) p 1/4
Consider the following for the next two
(02) items that follow: 159. What is the greatest value of k for which
The total monthly electricity bill for a house 2x2 4x + k = 0 has real roots?
consists of the sum of two parts, one part is [CDS-2024 (1)]
proportional to number of rooms and the (a) 1 (b) 2
other part is proportional to number of (c) 3 (d) 4
units consumed. Rs.400 is the monthly
electricity bill for the a house with 8 rooms 160. If the sum and product of the roots of n
and consuming 240 units and Rs.320 is the
quadratic equation are 2 and 100
monthly electricity bill for a house with 6
respectively, then which one of the following
rooms and consuming 200 units.
is correct?
[CDS-2024 (1)]
154. What is the monthly electricity bill for a
(a) There are infinitely many such equations
house with m rooms and consuming n
having differing roots
units?
(b) There is only one such equation which is
[CDS-2023 (2)]
x2 + 2x 100 = 0
(a) Rs.(40m + n) (b) Rs.(20m + n)
(c) There is only one such equation which is
40m n 30m n x2 2x 100 = 0
(c) Rs. (d) Rs.
2 2 (d) There is no such equation
CAPF PYQ
ANSWER KEY
1. c 2. d 3. a 4. c