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.
2. Perform the calculations:

[tex]\[
f(3) = -5(3)^2 - 3 + 20
\][/tex]

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

[tex]\[
3^2 = 9
\][/tex]

4. Multiply [tex]\( 9 \)[/tex] by [tex]\(-5\)[/tex]:

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

5. Add [tex]\(-3\)[/tex] to [tex]\(-45\)[/tex]:

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

6. Finally, add [tex]\(20\)[/tex] to [tex]\(-48\)[/tex]:

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

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