High School

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. 62
D. 64

Answer :

To find [tex]\( f(3) \)[/tex] for the function [tex]\( f(x) = -5x^2 - x + 20 \)[/tex], you need to substitute [tex]\( x = 3 \)[/tex] into the function and perform the calculations step by step. Here’s how to do it:

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

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

4. Subtract [tex]\( 3 \)[/tex]:

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

5. Add 20 to the result:

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

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