High School

11. Which of the following are results from multiplying [tex]-3x[/tex] by [tex]x^3 + 3x^2 - x - 5[/tex]?

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

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

C. [tex]-3x^4 + 3x^3 - 9x^2 - 5x[/tex]

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

Answer :

Let's work through the problem step-by-step to find the result of multiplying [tex]\(-3x\)[/tex] by [tex]\(x^3 + 3x^2 - x - 5\)[/tex].

1. Distribute [tex]\(-3x\)[/tex] across each term in the polynomial [tex]\(x^3 + 3x^2 - x - 5\)[/tex]:

- Multiply [tex]\(-3x\)[/tex] by [tex]\(x^3\)[/tex]:
[tex]\[
-3x \cdot x^3 = -3x^4
\][/tex]

- Multiply [tex]\(-3x\)[/tex] by [tex]\(3x^2\)[/tex]:
[tex]\[
-3x \cdot 3x^2 = -9x^3
\][/tex]

- Multiply [tex]\(-3x\)[/tex] by [tex]\(-x\)[/tex]:
[tex]\[
-3x \cdot (-x) = 3x^2
\][/tex]

- Multiply [tex]\(-3x\)[/tex] by [tex]\(-5\)[/tex]:
[tex]\[
-3x \cdot (-5) = 15x
\][/tex]

2. Combine all the results together:

The expanded polynomial is:
[tex]\[
-3x^4 - 9x^3 + 3x^2 + 15x
\][/tex]

3. Match the expanded expression with the given options:

The correct expression matches option:
- a. [tex]\(-3x^4 - 9x^3 + 3x^2 + 15x\)[/tex]

Therefore, the answer is a. [tex]\(-3x^4 - 9x^3 + 3x^2 + 15x\)[/tex].