High School

Multiply the polynomials:

[tex]\left(8x^2 + 6x + 8\right)(6x - 5)[/tex]

A. [tex]48x^3 - 76x^2 + 18x - 40[/tex]
B. [tex]48x^3 - 4x^2 + 18x + 40[/tex]
C. [tex]48x^3 - 4x^2 + 78x - 40[/tex]
D. [tex]48x^3 - 4x^2 + 18x - 40[/tex]

Answer :

To multiply the polynomials [tex]\((8x^2 + 6x + 8)\)[/tex] and [tex]\((6x - 5)\)[/tex], we'll use the distributive property, often called the FOIL method when dealing with binomials. Since one of them is a trinomial, we'll distribute each term separately:

1. Distribute [tex]\(8x^2\)[/tex]:

[tex]\[
8x^2 \cdot 6x = 48x^3
\][/tex]

[tex]\[
8x^2 \cdot (-5) = -40x^2
\][/tex]

2. Distribute [tex]\(6x\)[/tex]:

[tex]\[
6x \cdot 6x = 36x^2
\][/tex]

[tex]\[
6x \cdot (-5) = -30x
\][/tex]

3. Distribute [tex]\(8\)[/tex]:

[tex]\[
8 \cdot 6x = 48x
\][/tex]

[tex]\[
8 \cdot (-5) = -40
\][/tex]

Now, we combine all of these results together:

[tex]\[
48x^3 + (-40x^2) + 36x^2 + (-30x) + 48x + (-40)
\][/tex]

Let's combine like terms:

- Cubic term:
[tex]\[
48x^3
\][/tex]

- Quadratic terms:
[tex]\[
(-40x^2 + 36x^2) = -4x^2
\][/tex]

- Linear terms:
[tex]\[
(-30x + 48x) = 18x
\][/tex]

- Constant term:
[tex]\[
-40
\][/tex]

Putting it all together, the resulting polynomial is:

[tex]\[
48x^3 - 4x^2 + 18x - 40
\][/tex]

So, the correct answer is D. [tex]\(48x^3 - 4x^2 + 18x - 40\)[/tex].