Question

Write the value of k for which the quadratic equation x² – kx + 4 = 0 has equal roots.

Answer 1

The given quadratic equation is `x ^2 - kx + 4 = 0`, and roots are equal.

Then find the value of k.

Here, a = 1, b = -k and, c = 4

As we know that `D = b^2 - 4ac`

Putting the value of  a = 1, b = -k and c = 4

= `(-k)^2 - 4 xx 1 xx 4`

= `k^2- 16`

The given equation will have equal roots, if D = 0

`k^2 - 16 = 0`

`k^2 = 16`

`k = sqrt 16`

= ± 4

Therefore, the value of k = ± 4.