College

Simplify the following polynomial expression:

[tex]\left(5x^4 - 9x^3 + 7x - 1\right) + \left(-8x^4 + 4x^2 - 3x + 2\right) - \left(-4x^3 + 5x - 1\right)(2x - 7)[/tex]

A. [tex]11x^4 - 21x^3 + 14x^2 + 33x - 8[/tex]
B. [tex]11x^4 - 21x^3 + 14x^2 + 33x - 6[/tex]
C. [tex]5x^4 - 37x^3 - 6x^2 + 41x - 8[/tex]
D. [tex]5x^4 - 37x^3 - 6x^2 + 41x - 6[/tex]

Answer :

Certainly! To simplify the given polynomial expression, follow these steps:

1. Identify the parts of the expression:

We have three polynomial expressions:

- [tex]\(5x^4 - 9x^3 + 7x - 1\)[/tex]
- [tex]\(-8x^4 + 4x^2 - 3x + 2\)[/tex]
- [tex]\((-4x^3 + 5x - 1)(2x - 7)\)[/tex]

2. Expand the product in the third polynomial:

Consider the expression [tex]\((-4x^3 + 5x - 1)(2x - 7)\)[/tex]. We'll expand it by distributing each term from the first polynomial to each term of the second polynomial:

- [tex]\(-4x^3 \times 2x = -8x^4\)[/tex]
- [tex]\(-4x^3 \times -7 = 28x^3\)[/tex]
- [tex]\(5x \times 2x = 10x^2\)[/tex]
- [tex]\(5x \times -7 = -35x\)[/tex]
- [tex]\(-1 \times 2x = -2x\)[/tex]
- [tex]\(-1 \times -7 = 7\)[/tex]

Combine the [tex]\(x\)[/tex] terms:

- [tex]\( -35x - 2x = -37x\)[/tex]

Now, the expanded form of [tex]\((-4x^3 + 5x - 1)(2x - 7)\)[/tex] becomes:

[tex]\(-8x^4 + 28x^3 + 10x^2 - 37x + 7\)[/tex]

3. Combine all polynomials:

Now, we will subtract the expanded polynomial from the sum of the first two polynomials:

[tex]\[
(5x^4 - 9x^3 + 7x - 1) + (-8x^4 + 4x^2 - 3x + 2) - (-8x^4 + 28x^3 + 10x^2 - 37x + 7)
\][/tex]

4. Perform the additions and subtractions:

- For the [tex]\(x^4\)[/tex] term:
[tex]\[
5x^4 - 8x^4 + 8x^4 = 5x^4
\][/tex]
- For the [tex]\(x^3\)[/tex] term:
[tex]\[
-9x^3 - 0x^3 - 28x^3 = -37x^3
\][/tex]
- For the [tex]\(x^2\)[/tex] term:
[tex]\[
0x^2 + 4x^2 - 10x^2 = -6x^2
\][/tex]
- For the [tex]\(x\)[/tex] term:
[tex]\[
7x - 3x + 37x = 41x
\][/tex]
- For the constant term:
[tex]\[
-1 + 2 - 7 = -6
\][/tex]

5. Write the simplified expression:

The simplified polynomial expression is:

[tex]\[
5x^4 - 37x^3 - 6x^2 + 41x - 6
\][/tex]

The answer matches option D.

Answer: D. [tex]\(5x^4 - 37x^3 - 6x^2 + 41x - 6\)[/tex]