Quadratic Equations Exercise

Quadratic Equations Test:

The roots of the equation ix2 – 4x – 4i = 0 are
(a) –2i
(b) 2i
(c) –2i, –2i
(d) 2i, 2i

Ans. (c)

Two students while solving a quadratic equation in x, one copied the constant term incorrectly and got the roots 3 and 2. The other copied the constant term and coefficient of x2 correctly as –6 and 1 respectively. The correct roots are
(a) 3, –2
(b) –3, 2
(c) –6, –1
(d) 6, –1

Ans. (d)

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If sin A, sin B, cos A are in G.P., then roots of x2 + 2x cot B + 1 = 0 are always
(a) Real
(b) Imaginary
(c) Greater than 1
(d) Equal

Ans. (a)

The  roots of the quadratic equation 2x2 + 3x + 1 = 0, are
(a) Irrational
(b) Rational
(c) Imaginary
(d) None of these

Ans. (b)

If a root of the equation x2 + px + 12 = 0 is 4, while the roots of the equation x2 + px + q = 0 are same, then the value of q will be
(a) 4
(b) 4/49
(c) 49/4
(d) None of these

Ans. (c)

Related: Mensurations formulas questions

Roots of the equation x2 + bx – c = 0 (b, c > 0) are
(a) Both positive
(b) Both negative
(c) Of opposite sign
(d) None of these

Ans. (c)

If the sum of the roots of the equation ax2 + bx + c = 0 be equal to the sum of their squares, then
(a) a(a + b) = 2bc
(b) c(a + c) = 2ab
(c) b(a + b) = 2ac
(d) b(a + b) = ac

Ans. (c)

If the roots of equation 5x2 – 7x + k = 0 are reciprocal to each other, then value of k is
(a) 5
(b) 2
(c) 1/5
(d) 1

Ans. (a)

Related: HCF and LCM word problems

The roots of the equation x2/3 + x1/3 – 2 = 0 are
(a) 1, 4
(b) 1, –4
(c) 1, –8
(d) 1, 8

Ans. (c)

The expression y = ax2 + bx + c has always the same sign as c if
(a) 4ac < b2
(b) 4ac > b2
(c) ac < b2
(d) ac > b2

Ans. (b)

If the roots of x2 – bx + c = 0 are two consecutive integers, then b2 – 4c is
(a) 1
(b) 2
(c) 3
(d) 4

Ans. (a)

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If one of the roots of  equation x2 + ax + 3 = 0 is 3 and one of the roots of the equation x2 + ax + b = 0 is three times the other root, then the value of b is equal to
(a) 3
(b) 4
(c) 2
(d) 1

Ans. (a)

If the roots of the equation ax2 + bx + c = 0 are reciprocal to each other,  then
(a) a – c = 0
(b) b – c = 0
(c) a + c = 0
(d) b + c = 0

Ans. (a)

The number which exceeds its positive square root by 12 is
(a) 9
(b) 16
(c) 25
(d) None of these

Ans. (b)

Related: Ratio and proportions problems

What is the sum of the squares of roots of x2 – 3x + 1 = 0
(a) 5
(b) 7
(c) 9
(d) 10

Ans. (b)

In the equation x3 + 3Hx + G = 0, if G and H are real and G2 + H3 > 0, then the roots are
(a) All real and equal
(b) All real and distinct
(c) One real and two imaginary
(d) All real and two equal

Ans. (c)

Roots of ax2 + b = 0 are real and distinct if
(a) ab > 0
(b) ab < 0
(c) a, b > 0
(d) a, b < 0

Ans. (b)

If x2 + y2 = 25, xy = 12, then x =
(a) {3, 4}
(b) {3, –3}
(c) {3, 4, –3, –4}
(d) {–3, –3}

Ans. (c)

Related: Average problems for practice

If the roots of equation x2 + px + q = 0 differ by 1, then
(a) p2 = 4q
(b) p2 = 4q + 1
(c) p2 = 4q – 1
(d) None of these

Ans. (b)

Two students while solving a quadratic equation in x, one copied the constant term incorrectly and got the roots 3 and 2. The other copied the constant term and coefficient of x2 correctly as –6 and 1 respectively. The correct roots are
(a) 3, –2
(b) –3, 2
(c) –6, –1
(d) 6, –1

Ans. (d)

If x be real, then the minimum value of x2 – 8x + 17 is
(a) –1
(b) 0
(c) 1
(d) 2

Ans. (c)

Roots of the equations 2x2 – 5x + 1 = 0, x2 + 5x + 2 = 0 are
(a) Reciprocal and of same sign
(b) Reciprocal and of opposite sign
(c) Equal in product
(d) None of these

Ans. (b)

Related: arithmetic operation questions and answers

The number of solutions of log4 (x – 1) = log2 (x – 3)
(a) 3
(b) 1
(c) 2
(d) 0

Ans. (b)

If the quadratic equations ax2 + 2cx + b = 0 and ax2 + 2bx + c = 0 have a  common root, then a + 4b + 4c =
(a) –2
(b) –1
(c) 0
(d) 1

Ans. (c)

If one root of ax2 + bx + c = 0 be square of the other, then the value of b3 + ac2 + a2c is
(a) 3abc
(b) –3abc
(c) 0
(d) None of these

Ans. (a)

If x2 + px + 1 is a factor of the expression ax3 + bx + c, the
(a) a2 + c2 = –ab
(b) a2 – c2 = –ab
(c) a2 – c2 = ab
(d) None of these

Ans. (c)

Related: Percentage questions

The number of roots of the equation | x |2 – 7 | x | + 12 = 0 is
(a) 1
(b) 2
(c) 3
(d) 4

Ans. (d)

The number of quadratic equations which remains unchanged by squaring their roots is
(a) 2
(b) 4
(b) 6
(d) Infinite many

Ans. (a)

The number of solutions for the equation  x2 – 5 | x | + 6 = 0 is
(a) 4
(b) 3
(c) 2
(d) 1

Ans. (a)

Let two numbers have arithmetic mean 9 and geometric mean 4. Then these numbers are the roots of the quadratic equation
(a) x2 – 18x – 16 = 0
(b) x2 – 18x + 16 = 0
(c) x2 + 18x – 16 = 0
(d) x2 + 18x + 16 = 0

Ans. (b)

Related: Quadrilaterals questions

If a + b + c = 0, then the roots of the equation 4x2 + 3bx + 2c = 0 are
(a) Equal
(b) Imaginary
(c) Real
(d) None of these

Ans. (c)

If the roots of the equation x2 + 2mx + m2 – 2m + 6 = 0 are same, then the value of m will be
(a) 3
(b) 0
(c) 2
(d) –1

Ans. (a)

The number of values of  for which the equation x2 – 3x + k = 0 has two real and distinct roots lying in the interval (0, 1), are
(a) 0
(b) 2
(c) 3
(d) Infinitely many

Ans. (a)

Product of real roots of the equation t2x2 + | x | + 9 = 0
(a) Is always positive
(b) Is always negative
(c) Does not exist
(d) None of these

Ans. (c)

Related: Polynomials questions

The equation ex – x – 1 = 0 has
(a) Only one real root x = 0
(b) At least two real roots
(c) Exactly two real roots
(d) Infinitely many real roots

Ans. (a)

If the product of roots of the equation, mx2 + 6x + (2m – 1) = 0 is –1, then the value of m will be
(a) 1
(b) – 1
(c) 1/3
(d) – 1/3

Ans. (c)

The value of k for which 2x2 – kx + x + 8 = 0 has equal and real roots are
(a) –9 and –7
(b) 9 and 7
(c) –9 and 7
(d) 9 and –7

Ans. (d)

The roots of 4x2 + 6px + 1 = 0 are equal, then the value of p is
(a) 4/5
(b) 1/3
(c) 2/3
(d) 4/3

Ans. (c)

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