Question

Values of k for which the quadratic equation 2x - kx + k 0 has equal roots is

a)0only
b)4
c)8 only
d)0,8​

Answer 1

The answer is D.

Explanation:

We have to apply Discriminant Law. When a quadratic equation, ax² + bx + c = 0 has equal roots so the discriminant will be 0. Then, you have to substitute the values into the formula :

`D = {b}^(2) - 4ac`

`let \: D = 0 ,a = 2,b = k,c = k`

`0 = {k}^(2) - 4(2)(k)`

`{k}^(2) - 8k = 0`

`k(k - 8) = 0`

`k = 0`

`k - 8 = 0`

`k = 8`