College

What is the product?

[tex]\left(7x^2\right)\left(2x^3+5\right)\left(x^2-4x-9\right)[/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 expressions [tex]\((7x^2)(2x^3 + 5)(x^2 - 4x - 9)\)[/tex], we can follow these steps:

1. Multiply the first two expressions:

- Start with [tex]\((7x^2)\)[/tex] and [tex]\((2x^3 + 5)\)[/tex].

- Use the distributive property:
[tex]\(7x^2 \cdot (2x^3 + 5) = 7x^2 \cdot 2x^3 + 7x^2 \cdot 5\)[/tex].

- Simplify each term:
- [tex]\(7x^2 \cdot 2x^3 = 14x^5\)[/tex].
- [tex]\(7x^2 \cdot 5 = 35x^2\)[/tex].

So, the result of multiplying the first two expressions is:
[tex]\(14x^5 + 35x^2\)[/tex].

2. Multiply the result with the third expression:

- Now multiply [tex]\((14x^5 + 35x^2)\)[/tex] by [tex]\((x^2 - 4x - 9)\)[/tex].

- Use the distributive property again for each term in the first expression:

- Multiply [tex]\(14x^5\)[/tex] by each term in [tex]\((x^2 - 4x - 9)\)[/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].

- Multiply [tex]\(35x^2\)[/tex] by each term in [tex]\((x^2 - 4x - 9)\)[/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].

3. Combine all the terms:

Now, list all the resulting terms together:
[tex]\[
14x^7 - 56x^6 - 126x^5 + 35x^4 - 140x^3 - 315x^2.
\][/tex]

This is the final product of the given expressions.