If [tex]f(x) = 5x + 40[/tex], what is [tex]f(x)[/tex] when [tex]x = -5[/tex]?

A. [tex]-9[/tex]
B. [tex]-8[/tex]
C. [tex]7[/tex]
D. [tex]15[/tex]



Answer :

To determine the value of [tex]\( f(x) \)[/tex] when [tex]\( x = -5 \)[/tex] for the function [tex]\( f(x) = 5x + 40 \)[/tex], follow these steps:

1. Start with the given function [tex]\( f(x) = 5x + 40 \)[/tex].
2. Substitute [tex]\( x = -5 \)[/tex] into the function:
[tex]\[ f(-5) = 5(-5) + 40 \][/tex]
3. Calculate [tex]\( 5(-5) \)[/tex]:
[tex]\[ 5 \times -5 = -25 \][/tex]
4. Add 40 to the result:
[tex]\[ -25 + 40 = 15 \][/tex]
5. Therefore, the value of [tex]\( f(x) \)[/tex] when [tex]\( x = -5 \)[/tex] is [tex]\( 15 \)[/tex].

Hence, the correct answer is [tex]\( \boxed{15} \)[/tex].