College

Given the function [tex]$f(x)=-5x^2-x+20$[/tex], find [tex]$f(3)$[/tex].

A. [tex]-28[/tex]
B. [tex]-13[/tex]
C. [tex]62[/tex]
D. [tex]64[/tex]

Answer :

To find [tex]\( f(3) \)[/tex] for the function [tex]\( f(x) = -5x^2 - x + 20 \)[/tex], follow these steps:

1. Substitute 3 for [tex]\( x \)[/tex] in the function:
[tex]\[
f(3) = -5(3)^2 - (3) + 20
\][/tex]

2. Calculate [tex]\( 3^2 \)[/tex]:
[tex]\[
3^2 = 9
\][/tex]

3. Multiply by -5:
[tex]\[
-5 \times 9 = -45
\][/tex]

4. Substitute back into the expression:
[tex]\[
f(3) = -45 - 3 + 20
\][/tex]

5. Combine the terms step by step:
- First combine [tex]\(-45\)[/tex] and [tex]\(-3\)[/tex]:
[tex]\[
-45 - 3 = -48
\][/tex]

- Then add 20:
[tex]\[
-48 + 20 = -28
\][/tex]

Therefore, [tex]\( f(3) = -28 \)[/tex].