Question

Which of the following quadratic equation have rational roots? (a) x2 + x – 1 = 0 (b) x2 – 5x + 6 = 0 (c) 4x2 – 3x – 2 = 0 (d) 6x2 – x + 11 = 0​

Answer 1

$\bold{ANSWER≈}$

Let the roots of the first and second equations are (α,4β) and (α,3β) respectively

∴ product of the roots are 4αβ=a ....(1)

and 3αβ=6⇒αβ=2

⇒a=8 . ....From eqn (1)

Therefore, the roots of the equation x

2

−6x+8=0 are (2,4).

Given that the other roots of the first and second equations are integers, so if α=4⇒β=

2

1

In this case 3β is not integer.

Therefore, common root will be α=2

Answer 2

Answer:

THE ANS IS OPTION [C]

Step-by-step explanation:

JUST SUBSTITUTE THE VALUE IN THE FORM OF
D= B^2 - 4AC

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