Question

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

Answer 1

Answer:

168

Step-by-step explanation:

We would like to multiply these two expressions together and then substitute -2 in for x to solve.

f(x) * g(x) = (8 - 10x) * (5x + 4)

We will use FOIL (first, outer, inner last):

(8 - 10x) * (5x + 4) = 8 * 5x + 8 * 4 + (-10x) * 5x + (-10x) * 4

Combining terms, we get:

f(x) * g(x) = 32 - 50x²

Plug -2 in for x:

32 - 50 * (-2)² = 32 - 50 * 4 = 32 - 200 = -168

The answer is thus 168.

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