College

What is the sum of the polynomials?

[tex]\left(7x^3 - 4x^2\right) + \left(2x^3 - 4x^2\right)[/tex]

A. [tex]5x^3[/tex]
B. [tex]9x^3[/tex]
C. [tex]5x^3 - 8x^2[/tex]
D. [tex]9x^3 - 8x^2[/tex]

Answer :

To find the sum of the polynomials [tex]\((7x^3 - 4x^2) + (2x^3 - 4x^2)\)[/tex], follow these steps:

1. Combine the like terms:

First, identify the like terms in each polynomial.
- The terms involving [tex]\(x^3\)[/tex] are [tex]\(7x^3\)[/tex] and [tex]\(2x^3\)[/tex].
- The terms involving [tex]\(x^2\)[/tex] are [tex]\(-4x^2\)[/tex] and [tex]\(-4x^2\)[/tex].

2. Add the coefficients of the like terms:

- For the [tex]\(x^3\)[/tex] terms: [tex]\(7 + 2 = 9\)[/tex]. Hence, the [tex]\(x^3\)[/tex] term in the sum is [tex]\(9x^3\)[/tex].
- For the [tex]\(x^2\)[/tex] terms: [tex]\(-4 + (-4) = -8\)[/tex]. Hence, the [tex]\(x^2\)[/tex] term in the sum is [tex]\(-8x^2\)[/tex].

3. Write the resulting polynomial:

Combine the results from step 2 to form the sum of the polynomials:
[tex]\[
9x^3 - 8x^2
\][/tex]

4. Select the correct answer from the options provided:

From the options given:
- [tex]\(5x^3\)[/tex]
- [tex]\(9x^3\)[/tex]
- [tex]\(5x^3 - 8x^2\)[/tex]
- [tex]\(9x^3 - 8x^2\)[/tex]

We see that [tex]\(9x^3 - 8x^2\)[/tex] matches the result we obtained.

Therefore, the sum of the polynomials [tex]\((7x^3 - 4x^2) + (2x^3 - 4x^2)\)[/tex] is:

[tex]\[
\boxed{9x^3 - 8x^2}
\][/tex]