High School

Which of the following expressions is equivalent to [tex]-4x^3 - 12x^3 + 9x^2[/tex]?

A. [tex]x^8[/tex]
B. [tex]-7x^8[/tex]
C. [tex]-8x^3 + 9x^2[/tex]
D. [tex]-16x^3 + 9x^2[/tex]
E. [tex]-16x^6 + 9x^2[/tex]

Answer :

Certainly! Let's simplify the given expression step by step to find which of the options matches it:

The original expression is:
[tex]\[ -4x^3 - 12x^3 + 9x^2 \][/tex]

1. Combine Like Terms:

Start by combining the terms that have the same power of [tex]\( x \)[/tex]. Here, the terms [tex]\(-4x^3\)[/tex] and [tex]\(-12x^3\)[/tex] are like terms:
[tex]\[
-4x^3 - 12x^3 = -16x^3
\][/tex]

So the expression becomes:
[tex]\[
-16x^3 + 9x^2
\][/tex]

2. Factor the Expression:

Notice that both terms have a common factor of [tex]\( x^2 \)[/tex]. We can factor out [tex]\( x^2 \)[/tex] from the expression:
[tex]\[
-16x^3 + 9x^2 = x^2(-16x + 9)
\][/tex]

Thus, the expression simplifies to:
[tex]\[
x^2(9 - 16x)
\][/tex]

3. Match the Simplified Expression:

Our simplified expression is [tex]\( x^2(9 - 16x) \)[/tex]. If we compare it to the given choices, it matches the form of:
[tex]\[
-16x^3 + 9x^2
\][/tex]

So, the expression [tex]\(-16x^3 + 9x^2\)[/tex] is equivalent to the simplified version of the original expression. This is the correct choice.