Question

If f(x) = 8 – 10x and g(x) = 5x + 4, what is the value of (fg)(–2)?

Answer 1

f(-2)=8-10*(-2)=28
g(-2)=5(-2)+4=-6
fg(-2)=168

Answer 2

(fg)(x) = -168

Explanation:

Since (fg)(x) = f(g)×g(x)

So (fg)(-2) = f(-2)×g(-2)

Since f(x) = 8 - 10x

f(-2) = 8 - 10(-2)

= 8 + 20

= 28

and g(x) = 5x + 4

g(-2) = 5(-2) + 4

= -10 + 4

= -6

Now f(-2)×g(-2) = 28(-6) = -168

Therefore, (fg)(x) = -168 will be the answer.