Given f(x) = x2 + 8x – 20 and g(x) = 4x – 10, what is (f ° g)(x)?

Question

A= 4x² + 32x - 90

B =16x² - 48x

C=16x²+ 32x – 200

D= 4X²+ 22x²– 160x + 200 

Answer 1

so what you want is f(g(x)) so you want to take the equation g(x) and plug it in wherever you see an x in the f(x) equation:

f(g(x))=(4x-10)²+8(4x-10)-20 = 16x²-80x+100+32x-80-20 = 16x²-48x (Choice B)

Answer 2

Well substitute 4x-10 for x in f(x)

fg (x) = (4x-10)^2 + 8 (4x-10) - 20

The squared term here will be (4x)^2 = 16x^2, so it has to be b or c

The constant term will be (-10)^2 - 80 - 20 = 0

So it's going to be B