Question

Given f(x)=4x2−5 and g(x)=x+3 . What is (fg)(x) ?

Answer 1

I just took the test, it was A. 4x^3+12x^2-5x-15 :)

Answer 2

Answer:

$(fg)(x)=4x^3+12x^2-5x-15$

First option is correct.

Step-by-step explanation:

We have been given that

$f(x)=4x^2-5$

$g(x)=x+3$

We know that $(fg)(x)=f(x)g(x)$

Hence, we have to find the product of f(x) and g(x)

$(fg)(x)=(4x^2-5)(x+3)$

Apply distributive property

$(fg)(x)=4x^2\cdot x+4x^2\cdot3-5x-5\cdot3$

Simplifying, we get

$(fg)(x)=4x^3+12x^2-5x-15$

First option is correct.