Question

For what values of k, the roots of the equation x² + 4x +k = 0 are real? 

Answer 1

x² +4x +k=0 

∴ Roots of given equation are real,

D≥0

implies that 

(4)² - 4 ×k ≥ 0

implies that 

-4k ≥ -16

implies that 

k ≤ 4

∴ k has all real values k ≤ 4.