College

Given the function [tex]f(x) = 5x^2 - 9x + 18[/tex], find [tex]f(3)[/tex].

A. [tex]f(3) = 31[/tex]

B. [tex]f(3) = 36[/tex]

C. [tex]f(3) = 49[/tex]

D. [tex]f(3) = 85[/tex]

Answer :

To find [tex]\( f(3) \)[/tex] for the function [tex]\( f(x) = 5x^2 - 9x + 18 \)[/tex], follow these steps:

1. Substitute [tex]\( x = 3 \)[/tex] into the function:
[tex]\[
f(3) = 5(3)^2 - 9(3) + 18
\][/tex]

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

3. Multiply the result by 5:
[tex]\[
5 \times 9 = 45
\][/tex]

4. Multiply 9 by 3:
[tex]\[
9 \times 3 = 27
\][/tex]

5. Substitute these values back into the equation:
[tex]\[
f(3) = 45 - 27 + 18
\][/tex]

6. Perform the subtraction:
[tex]\[
45 - 27 = 18
\][/tex]

7. Add the remaining value:
[tex]\[
18 + 18 = 36
\][/tex]

Thus, the value of [tex]\( f(3) \)[/tex] is 36. Therefore, the correct answer is [tex]\( \boxed{36} \)[/tex], which corresponds to option B.