Question

Let $$a, b, c$$  be three real numbers such that $$2a + 3b + 6c = 0.$$    Then the quadratic equation $$a{x^2} + bx + c = 0$$    has

A. imaginary roots
B. at least one root in $$(0, 1)$$  
C. at least one root in $$(- 1, 0)$$
D. both roots in $$(1, 2)$$
Answer :   at least one root in $$(0, 1)$$
Solution :
Take the equation $$2a{x^3} + 3b{x^2} + 6cx = 0.$$     Clearly, $$x = 0, 1$$   are two roots. Observe that $$a{x^2} + bx + c = 0$$    is the derived equation. So, one root lies between 0 and 1.

Releted MCQ Question on
Algebra >> Quadratic Equation

Releted Question 1

If $$\ell ,m,n$$  are real, $$\ell \ne m,$$  then the roots by the equation: $$\left( {\ell - m} \right){x^2} - 5\left( {\ell + m} \right)x - 2\left( {\ell - m} \right) = 0$$         are

A. Real and equal
B. Complex
C. Real and unequal
D. None of these
Releted Question 2

The equation $$x + 2y + 2z = 1{\text{ and }}2x + 4y + 4z = 9{\text{ have}}$$

A. Only one solution
B. Only two solutions
C. Infinite number of solutions
D. None of these
Releted Question 3

Let $$a > 0, b > 0$$    and $$c > 0$$ . Then the roots of the equation $$a{x^2} + bx + c = 0$$

A. are real and negative
B. have negative real parts
C. both (A) and (B)
D. none of these
Releted Question 4

Both the roots of the equation $$\left( {x - b} \right)\left( {x - c} \right) + \left( {x - a} \right)\left( {x - c} \right) + \left( {x - a} \right)\left( {x - b} \right) = 0$$           are always

A. positive
B. real
C. negative
D. none of these.

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Quadratic Equation


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