High School

What is the simplest form of [tex]\left(4x^3 + 6x - 7\right) + \left(3x^3 - 5x^2 - 5x\right)[/tex]?

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

Answer :

We start with the two polynomials:

[tex]$$
4x^3 + 6x - 7 \quad \text{and} \quad 3x^3 - 5x^2 - 5x.
$$[/tex]

Our goal is to add these expressions together. Follow these steps:

1. Group the like terms.
Identify the terms with the same power of [tex]$x$[/tex]:

- The [tex]$x^3$[/tex] terms are [tex]$4x^3$[/tex] and [tex]$3x^3$[/tex].
- The [tex]$x^2$[/tex] term is [tex]$-5x^2$[/tex] (note that the first polynomial does not contain an [tex]$x^2$[/tex] term).
- The [tex]$x$[/tex] terms are [tex]$6x$[/tex] and [tex]$-5x$[/tex].
- The constant term is [tex]$-7$[/tex].

2. Add the [tex]$x^3$[/tex] terms:
[tex]$$
4x^3 + 3x^3 = 7x^3.
$$[/tex]

3. Add the [tex]$x^2$[/tex] terms:
[tex]$$
0 - 5x^2 = -5x^2.
$$[/tex]

4. Add the [tex]$x$[/tex] terms:
[tex]$$
6x - 5x = x.
$$[/tex]

5. Write down the constant term:
[tex]$$
-7.
$$[/tex]

6. Combine all the results:
The sum of the polynomials is

[tex]$$
7x^3 - 5x^2 + x - 7.
$$[/tex]

Among the provided choices, the expression that matches our result is:

[tex]$$
7x^3 - 5x^2 + x - 7.
$$[/tex]

This corresponds to the second option.