Question

Write the value of λ for which x² + 4x + λ is a perfect square.

Answer 1

The given quadric equation is x² + 4x + λ = 0

Then find the value of k.

Here, a = 1, b = 4 and c = λ

As we know that D = b² - 4ac

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

` = (4)^2 - 4 xx 1 xx λ`

= 16 - 4λ

The given equation is a perfect square, if D = 0

14 - 4λ = 0

4λ = 16

`λ = 16/4`

= 4

Therefore, the value of λ = 4.