Question

Express your answer as a polynomial in standard form.

ƒ(x) = 2x² + 5x + 15
g(x) = -x + 5
Find: (fog)(x)

Answer 1

2x² - 25x + 90

Explanation:

→ Replace every x in 2x² + 5x + 15 with -x + 5

2 × ( -x + 5 )² + 5 ( -x + 5 ) + 15

→ Simplify

2 ( x² - 10x + 25 ) - 5x + 25 + 15

→ Expand

2x² - 20x + 50 - 5x + 40

→ Simplify

2x² -25x + 90