High School

Given [tex]$f(x) = 5x^2$[/tex] and [tex]$g(x) = x^3 + 2x^2 - 5x$[/tex], what is [tex]$f(x) \cdot g(x)$[/tex]?

A. [tex]5x^5 + 10x^4 - 25x^3[/tex]
B. [tex]5x^6 + 10x^4 - 25x^2[/tex]
C. [tex]-x^3 + 3x^2 + 5x[/tex]
D. [tex]x^3 + 7x^2 - 5[/tex]

Answer :

Sure, let's solve this step-by-step.

We have two functions:
[tex]\[ f(x) = 5x^2 \][/tex]
[tex]\[ g(x) = x^3 + 2x^2 - 5x \][/tex]

We need to find [tex]\( f(x) \cdot g(x) \)[/tex], which means we will multiply [tex]\( f(x) \)[/tex] by [tex]\( g(x) \)[/tex].

First, write down the multiplication:
[tex]\[ f(x) \cdot g(x) = (5x^2) \cdot (x^3 + 2x^2 - 5x) \][/tex]

Now distribute [tex]\( 5x^2 \)[/tex] to each term inside the parentheses:
[tex]\[ 5x^2 \cdot x^3 + 5x^2 \cdot 2x^2 + 5x^2 \cdot (-5x) \][/tex]

Now calculate each term separately:
1. [tex]\( 5x^2 \cdot x^3 = 5x^{2+3} = 5x^5 \)[/tex]
2. [tex]\( 5x^2 \cdot 2x^2 = 10x^{2+2} = 10x^4 \)[/tex]
3. [tex]\( 5x^2 \cdot (-5x) = -25x^{2+1} = -25x^3 \)[/tex]

So, combine these together:
[tex]\[ f(x) \cdot g(x) = 5x^5 + 10x^4 - 25x^3 \][/tex]

From the given choices, the correct answer is:
[tex]\[ \boxed{5x^5 + 10x^4 - 25x^3} \][/tex]