High School

What is the product?

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

A. [tex]14x^5-x^4-46x^3-58x^2-20x-45[/tex]

B. [tex]14x^6-56x^5-91x^4-140x^3-315x^2[/tex]

C. [tex]14x^7-56x^6-126x^5+35x^4-140x^3-315x^2[/tex]

D. [tex]14x^{12}-182x^6+35x^4-455x^2[/tex]

Answer :

To find the product of the expression [tex]\((7x^2)(2x^3 + 5)(x^2 - 4x - 9)\)[/tex], we will multiply the terms step-by-step. Let's break it down:

### Step 1: Multiply the first two expressions
First, we'll multiply [tex]\(7x^2\)[/tex] with [tex]\((2x^3 + 5)\)[/tex].

[tex]\[
7x^2 \times (2x^3 + 5) = 7x^2 \cdot 2x^3 + 7x^2 \cdot 5
\][/tex]

Calculating each term separately:

- [tex]\(7x^2 \cdot 2x^3 = 14x^{2+3} = 14x^5\)[/tex]
- [tex]\(7x^2 \cdot 5 = 35x^2\)[/tex]

So, the product of these two expressions is:

[tex]\[
14x^5 + 35x^2
\][/tex]

### Step 2: Multiply the result with the third expression
Now, multiply the result from Step 1, [tex]\((14x^5 + 35x^2)\)[/tex], with [tex]\((x^2 - 4x - 9)\)[/tex].

[tex]\((14x^5 + 35x^2) \times (x^2 - 4x - 9)\)[/tex] can be expanded as follows:

1. Distribute [tex]\(14x^5\)[/tex]:

- [tex]\(14x^5 \cdot x^2 = 14x^{5+2} = 14x^7\)[/tex]
- [tex]\(14x^5 \cdot (-4x) = -56x^{5+1} = -56x^6\)[/tex]
- [tex]\(14x^5 \cdot (-9) = -126x^5\)[/tex]

2. Distribute [tex]\(35x^2\)[/tex]:

- [tex]\(35x^2 \cdot x^2 = 35x^{2+2} = 35x^4\)[/tex]
- [tex]\(35x^2 \cdot (-4x) = -140x^{2+1} = -140x^3\)[/tex]
- [tex]\(35x^2 \cdot (-9) = -315x^2\)[/tex]

### Step 3: Combine all terms
Add all the terms together:

[tex]\[
14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2
\][/tex]

This is the product of the given expressions:

[tex]\[
14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2
\][/tex]

This completes the multiplication, and this expression is the final result.