Question

If one root of the equation x^2 + 5x + k = 0 is -2, what is the value of k?

Answer 1

k = 6

Explanation:

since x = - 2 put x = 2 into the equation

(- 2)² + 5(- 2) + k = 0

4 - 10 + k = 0

-6 + k = 0

+6 +6

k = 6

Answer 2

k = 6

Explanation:

given x = - 2 is a root then substitute x = 2 into the equation

(- 2)² + 5(- 2) + k = 0

4 - 10 + k = 0

- 6 + k = 0 ( add 6 to both sides )

k = 6