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 are perfect square, ifD = 0 

14 - 4λ = 0

       4λ = 16

       `λ = 16/4`

           = 4

Therefore, the value of λ = 4.