Question

Without solving the following quadratic equation, find the value(s) of k for which the given equation has equal roots. x^2-(k+2)x + (k +5) =0​

Answer 1

The given equation has equal roots

⇒ Discriminant=b

2

−4ac=0

where a=2,b−(k−2),c=−1

⇒(k−2)

2

−4×2×1=0

⇒(k−2)

2

=8

⇒k−2=±

8

=±2

2

∴k=2±2

2