High School

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

A. -28
B. -13
C. 62
D. 64

Answer :

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

1. Substitute [tex]\( x = 3 \)[/tex] into 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 [tex]\(-5\)[/tex]:

[tex]\[
-5 \times 9 = -45
\][/tex]

4. Substitute back into the function:

[tex]\[
f(3) = -45 - 3 + 20
\][/tex]

5. Simplify the expression step by step:

- First, add [tex]\(-45\)[/tex] and [tex]\(-3\)[/tex] together:

[tex]\[
-45 - 3 = -48
\][/tex]

- Then add [tex]\(20\)[/tex]:

[tex]\[
-48 + 20 = -28
\][/tex]

Therefore, the value of [tex]\( f(3) \)[/tex] is [tex]\(-28\)[/tex].