Question

If the equation x² + 4x + k = 0 has real and distinct roots, then
(A) k < 4
(B) k > 4
(C) k ≥ 4
(D) k ≤ 4

Answer 1

Answer: (A) k < 4

The given equation is x² + 4x + k = 0

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

D = b² – 4ac

= (4)² – 4 x 1 x k

= 16 – 4k

The given equation will have real and distinct roots, if

D > 0

16 – 4k > 0

16 > 4k

4k < 16

k < 16/4

k < 4