College

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

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

Answer :

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

1. Identify the function:
The function provided is [tex]\( f(x) = -5x^2 - x + 20 \)[/tex].

2. Substitute [tex]\( x = 3 \)[/tex] into the function:
Replace every [tex]\( x \)[/tex] in the function with 3. This gives us:
[tex]\[
f(3) = -5(3)^2 - 3 + 20
\][/tex]

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

4. Multiply by [tex]\(-5\)[/tex]:
[tex]\[
-5 \times 9 = -45
\][/tex]

5. Continue with the expression:
Substituting back, we now have:
[tex]\[
f(3) = -45 - 3 + 20
\][/tex]

6. Calculate [tex]\(-45 - 3 \)[/tex]:
[tex]\[
-45 - 3 = -48
\][/tex]

7. Add 20 to [tex]\(-48\)[/tex]:
[tex]\[
-48 + 20 = -28
\][/tex]

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