Question

If f(x) = 4x ^ 2 and g(x) = x + 1 , find (fg)(x) ).

a. 4x(x)
B. 4x ^ 3 + 4x ^ 2
C. 4(x + 1) ^ 2
D. 4x ^ 2 + 1

Answer 1

`\boxed{\sf \ C \ is \ the \ correct \ answer \ ! \ }`

Explanation:

fog(x)=f(g(x))

so it comes

`f(g(x))=f(x+1)=4(x+1)^2`

so C is the correct answer

Answer 2

Option B

Explanation:

`f(x) = 4x^2\\g(x) = x+1`

Multiplying both will give us:

`(fg)(x) = 4x^2(x+1)`

=>
`(fg)(x) = 4x^3+4x^2`