5. Multiply [tex]\left(5x^2 + x - 4\right)(x + 2)[/tex]

A. [tex]5x^3 + x^2 - 4x - 8[/tex]
B. [tex]5x^3 + 11x^2 - 2x - 8[/tex]
C. [tex]5x^3 + 10x^2 - 4x - 8[/tex]
D. [tex]5x^3 + 20x^2 + 2x - 8[/tex]



Answer :

To multiply the polynomials [tex]\((5x^2 + x - 4)\)[/tex] and [tex]\((x + 2)\)[/tex], follow these steps:

1. Distribute each term of [tex]\(5x^2 + x - 4\)[/tex] with each term of [tex]\(x + 2\)[/tex]:
- First, distribute [tex]\(5x^2\)[/tex] over [tex]\(x + 2\)[/tex]:
[tex]\[ 5x^2 \cdot x + 5x^2 \cdot 2 = 5x^3 + 10x^2 \][/tex]
- Next, distribute [tex]\(x\)[/tex] over [tex]\(x + 2\)[/tex]:
[tex]\[ x \cdot x + x \cdot 2 = x^2 + 2x \][/tex]
- Finally, distribute [tex]\(-4\)[/tex] over [tex]\(x + 2\)[/tex]:
[tex]\[ -4 \cdot x + (-4) \cdot 2 = -4x - 8 \][/tex]

2. Combine all the products:
[tex]\[ (5x^3 + 10x^2) + (x^2 + 2x) + (-4x - 8) \][/tex]

3. Combine like terms (group and simplify):
- Combine the [tex]\(x^2\)[/tex] terms:
[tex]\[ 10x^2 + x^2 = 11x^2 \][/tex]
- Combine the [tex]\(x\)[/tex] terms:
[tex]\[ 2x - 4x = -2x \][/tex]

4. Write the final expression:
[tex]\[ 5x^3 + 11x^2 -2x - 8 \][/tex]

Therefore, the product of the polynomials [tex]\((5x^2 + x - 4)\)[/tex] and [tex]\((x + 2)\)[/tex] is:
[tex]\[ \boxed{5x^3 + 11x^2 - 2x - 8} \][/tex]

Comparing it to the given answer choices, the correct answer is:
[tex]\[ 5x^3 + 11x^2 - 2x - 8 \][/tex]