College

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], you simply need to substitute [tex]\( x = 3 \)[/tex] into the function and calculate the result step-by-step:

1. Start by replacing [tex]\( x \)[/tex] with 3 in the function:

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

2. First, calculate [tex]\( 3^2 \)[/tex]:

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

3. Substitute back the squared value:

[tex]\[ f(3) = -5 \times 9 - 3 + 20 \][/tex]

4. Next, calculate [tex]\( -5 \times 9 \)[/tex]:

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

5. Substitute this product back into the equation:

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

6. Now, perform the subtraction and addition step-by-step:

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

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

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