College

Select the correct answer.

Which of these is the standard form of the following function?

[tex]f(x)=-9(x+5)^2+4[/tex]

A. [tex]f(x)=-9x^2-180x-221[/tex]

B. [tex]f(x)=-9x^2-90x-221[/tex]

C. [tex]f(x)=9x^2-90x-221[/tex]

D. [tex]f(x)=9x^2-180x+221[/tex]

Answer :

Sure, let's work through the problem step-by-step to find the standard form of the function [tex]\( f(x) = -9(x+5)^2 + 4 \)[/tex].

1. Expand [tex]\((x+5)^2\)[/tex]:

To expand [tex]\((x+5)^2\)[/tex], use the formula [tex]\((a+b)^2 = a^2 + 2ab + b^2\)[/tex].

[tex]\[
(x+5)^2 = x^2 + 2 \cdot 5 \cdot x + 5^2 = x^2 + 10x + 25
\][/tex]

2. Distribute [tex]\(-9\)[/tex] across the expanded form:

Now, multiply [tex]\(-9\)[/tex] with each term in the expansion:

[tex]\[
-9(x^2 + 10x + 25) = -9x^2 - 90x - 225
\][/tex]

3. Add 4 to the result:

Finally, add the constant term 4 to the expanded and multiplied expression:

[tex]\[
-9x^2 - 90x - 225 + 4 = -9x^2 - 90x - 221
\][/tex]

So, the standard form of the given function is:

[tex]\[
f(x) = -9x^2 - 90x - 221
\][/tex]

This matches the second option in your list:

[tex]\[
f(x) = -9x^2 - 90x - 221
\][/tex]