Answer:
see explanation
Step-by-step explanation:
If (x + a) is a factor of polynomial f(x) , then f(- a) = 0
So if (x + 6) is a factor of f(x), then f(- 6) = 0
f(x) = 2x² + 8x - 24 , then
f(- 6) = 2(- 6)² + 8(- 6) - 24 = 2(36) - 48 - 24 = 72 - 48 - 24 = 0
Then (x + 6) is a factor of f(x)
