Given f(x)=2x2−3 and g(x)=x+4 . What is (fg)(x) ?
A)2x3−12
B)2x2+x+1
C) 2x3+8x2−3x−12
D) −2x2+x+7

Respuesta :


 [tex] (fg)(x)=f(x)g(x)=(2x^2−3)(x+4)=2x^3+8x^2-3x-12[/tex]

or

(fg)(x)=f(x)g(x)=(2x^2−3)(x+4)=2x^3+8x^2-3x-12

Answer :

Option (c) is correct  

[tex](fg)(x)=2x^3+8x^2-3x-12[/tex]  

Step-by-step explanation:  

Given : functions [tex]f(x)=2x^2-3[/tex] and [tex]g(x)=x+4[/tex]  

We have to calculate (fg)(x) and choose the correct from the given options.  

Consider (fg)(x) = (f • g)(x) = f(x) • g(x)  

That is we have to multiply the two functions.  

Consider the given functions [tex]f(x)=2x^2-3[/tex] and [tex]g(x)=x+4[/tex]  

Then,  

[tex]f(x)\cdot g(x) =(2x^2-3)(x+4)[/tex]  

Multiply the each term of first bracket with each term of second bracket, we have,  

[tex]f(x)\cdot g(x) =2x^2\cdot (x+4)-3\cdot(x+4)[/tex]  

Simplify, we have,  

[tex]f(x)\cdot g(x) =2x^3+8x^2-3x-12[/tex]  

Thus, [tex](fg)(x)=2x^3+8x^2-3x-12[/tex]  

Option (c) is correct.