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 :

Sure! Let's find the product of the expression step-by-step.

Given expression:
[tex]\[
\left(7 x^2\right)\left(2 x^3 + 5\right)\left(x^2 - 4 x - 9\right)
\][/tex]

We need to multiply these three expressions together. To do this systematically, we can follow these steps:

1. Multiply the first two expressions:
[tex]\[
\left(7 x^2\right)\left(2 x^3 + 5\right)
\][/tex]

Distribute [tex]\(7x^2\)[/tex] to each term inside the parentheses:
[tex]\[
(7 x^2) \cdot (2 x^3) + (7 x^2) \cdot (5)
\][/tex]

Calculate each term:
[tex]\[
7 x^2 \cdot 2 x^3 = 14 x^5
\][/tex]
[tex]\[
7 x^2 \cdot 5 = 35 x^2
\][/tex]

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

2. Multiply the result by the third expression:
[tex]\[
\left(14 x^5 + 35 x^2\right) \left(x^2 - 4 x - 9\right)
\][/tex]

Distribute each term in the first polynomial to every term in the second polynomial:
[tex]\[
(14 x^5) \cdot (x^2) + (14 x^5) \cdot (-4 x) + (14 x^5) \cdot (-9)
+
(35 x^2) \cdot (x^2) + (35 x^2) \cdot (-4 x) + (35 x^2) \cdot (-9)
\][/tex]

Calculate each term:
[tex]\[
14 x^5 \cdot x^2 = 14 x^7
\][/tex]
[tex]\[
14 x^5 \cdot (-4 x) = -56 x^6
\][/tex]
[tex]\[
14 x^5 \cdot (-9) = -126 x^5
\][/tex]
[tex]\[
35 x^2 \cdot x^2 = 35 x^4
\][/tex]
[tex]\[
35 x^2 \cdot (-4 x) = -140 x^3
\][/tex]
[tex]\[
35 x^2 \cdot (-9) = -315 x^2
\][/tex]

3. Combine all terms to get the final expression:
[tex]\[
14 x^7 - 56 x^6 - 126 x^5 + 35 x^4 - 140 x^3 - 315 x^2
\][/tex]

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