High School

Multiply the following expressions:

[tex]\left(x^2-5x\right)\left(2x^2+x-3\right)[/tex]

A. [tex]2x^4-9x^3-8x^2+15x[/tex]

B. [tex]4x^4+9x^3-8x^2+15x[/tex]

C. [tex]2x^4+9x^3-8x^2+15x[/tex]

D. [tex]2x^4-9x^3-9x^2-15x[/tex]

Answer :

To multiply the two polynomials [tex]\((x^2 - 5x)\)[/tex] and [tex]\((2x^2 + x - 3)\)[/tex], we need to use the distributive property. Here is how we can do it step by step:

1. Distribute each term in the first polynomial to each term in the second polynomial:

- Multiply [tex]\(x^2\)[/tex] by each term in [tex]\(2x^2 + x - 3\)[/tex]:
- [tex]\(x^2 \cdot 2x^2 = 2x^4\)[/tex]
- [tex]\(x^2 \cdot x = x^3\)[/tex]
- [tex]\(x^2 \cdot (-3) = -3x^2\)[/tex]

- Multiply [tex]\(-5x\)[/tex] by each term in [tex]\(2x^2 + x - 3\)[/tex]:
- [tex]\(-5x \cdot 2x^2 = -10x^3\)[/tex]
- [tex]\(-5x \cdot x = -5x^2\)[/tex]
- [tex]\(-5x \cdot (-3) = 15x\)[/tex]

2. Combine all the terms you've obtained:

[tex]\[
2x^4 + x^3 - 3x^2 - 10x^3 - 5x^2 + 15x
\][/tex]

3. Combine like terms:

- Combine the [tex]\(x^3\)[/tex] terms: [tex]\(x^3 - 10x^3 = -9x^3\)[/tex]
- Combine the [tex]\(x^2\)[/tex] terms: [tex]\(-3x^2 - 5x^2 = -8x^2\)[/tex]

4. Write down the final polynomial:

[tex]\[
2x^4 - 9x^3 - 8x^2 + 15x
\][/tex]

The correct answer is [tex]\(2x^4 - 9x^3 - 8x^2 + 15x\)[/tex], which corresponds to option A.