High School

Use vertical multiplication to find the product of:

[tex]
\begin{array}{r}
x^3 + 2x + 3 \\
\times \quad x^3 - x + 1 \\
\end{array}
[/tex]

A. [tex]x^6 + x^4 + 4x^3 - 2x^2 - x + 3[/tex]

B. [tex]x^6 - x^4 + x^3 - 2x^2 + 2x + 3[/tex]

C. [tex]x^6 + 2x^3 - 2x^2 + 2x + 1[/tex]

D. [tex]x^6 + x^4 + 3x^3 - 2x^2 - 3x + 3[/tex]

Answer :

To find the product of the given polynomials using vertical multiplication, let's work through the steps:

We have two polynomials:
- [tex]\( P(x) = x^3 + 2x + 3 \)[/tex]
- [tex]\( Q(x) = x^3 - x + 1 \)[/tex]

Here's how you can multiply them step by step:

1. Align the polynomials for multiplication:
Write them vertically, like numbers, aligning similar terms:

```
x^3 + 0x^2 + 2x + 3
× x^3 + 0x^2 - x + 1
```

2. Multiply each term in the second polynomial by each term in the first polynomial:

- Multiply by 1 (rightmost term in the second polynomial):
- [tex]\( (x^3 + 2x + 3) \times 1 = x^3 + 2x + 3 \)[/tex]

- Multiply by [tex]\(-x\)[/tex]:
- [tex]\( (x^3 + 2x + 3) \times (-x) = -x^4 - 2x^2 - 3x \)[/tex]

- Multiply by 0 (0 is in [tex]\(x^2\)[/tex] place):
- This term becomes 0.

- Multiply by [tex]\(x^3\)[/tex]:
- [tex]\( (x^3 + 2x + 3) \times x^3 = x^6 + 2x^4 + 3x^3 \)[/tex]

3. Add all the results together: Align like terms and add:

```
x^6 + 2x^4 + 3x^3
-x^4 - 2x^2 - 3x
+x^3 + 2x + 3
----------------------------
x^6 + x^4 + 4x^3 - 2x^2 - x + 3
```

Therefore, the product of [tex]\((x^3 + 2x + 3)\)[/tex] and [tex]\((x^3 - x + 1)\)[/tex] is:

[tex]\(x^6 + x^4 + 4x^3 - 2x^2 - x + 3\)[/tex]

This matches option A, so the correct answer is:

A. [tex]\(x^6 + x^4 + 4x^3 - 2x^2 - x + 3\)[/tex]