College

What is the product?

\[ \left(7x^2\right)\left(2x^3 + 5\right)\left(x^2 - 4x - 9\right) \]

A. \( 14x^5 - x^4 - 46x^3 - 58x^2 - 20x - 45 \)

B. \( 14x^6 - 56x^5 - 91x^4 - 140x^3 - 315x^2 \)

C. \( 14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2 \)

D. \( 14x^{12} - 182x^6 + 35x^4 - 455x^2 \)

Answer :

Sure! Let's go through finding the product step by step.

We need to find the product of the following three expressions:
[tex]\[
(7x^2)(2x^3 + 5)(x^2 - 4x - 9)
\][/tex]

To solve this, we can follow these steps:
1. Start by multiplying the first two expressions.
2. Then multiply the result by the third expression.

### Step 1: Multiply the first two expressions

First two expressions:
[tex]\[
7x^2 \quad \text{and} \quad 2x^3 + 5
\][/tex]

Distribute [tex]\( 7x^2 \)[/tex] to each term in the second expression:
[tex]\[
7x^2 \cdot (2x^3 + 5) = (7x^2 \cdot 2x^3) + (7x^2 \cdot 5)
\][/tex]

Multiply the terms:
[tex]\[
7x^2 \cdot 2x^3 = 14x^5 \quad \text{and} \quad 7x^2 \cdot 5 = 35x^2
\][/tex]

So the result of the first multiplication is:
[tex]\[
14x^5 + 35x^2
\][/tex]

### Step 2: Multiply the result by the third expression

Now we have:
[tex]\[
(14x^5 + 35x^2) \quad \text{and} \quad (x^2 - 4x - 9)
\][/tex]

We'll use the distributive property again to multiply each term in the first polynomial by each term in the second polynomial:

[tex]\[
(14x^5 + 35x^2) \cdot (x^2 - 4x - 9) = 14x^5 \cdot (x^2 - 4x - 9) + 35x^2 \cdot (x^2 - 4x - 9)
\][/tex]

Now, let's distribute each term separately:

#### Distributing [tex]\( 14x^5 \)[/tex]:

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

#### Distributing [tex]\( 35x^2 \)[/tex]:

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

### Step 3: Combine all the terms

Now, we combine all the resulting terms:

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

So, the final product is:
[tex]\[
14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2
\][/tex]

Thus, the correct answer is:
[tex]\[
14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2
\][/tex]