College

Given the function [tex]f(x) = 4|x-5| + 3[/tex], for what values of [tex]x[/tex] is [tex]f(x) = 15[/tex]?

A. [tex]x = 0.5, x = 7.5[/tex]
B. [tex]x = 2, x = 7.5[/tex]
C. [tex]x = 2, x = 8[/tex]
D. [tex]x = 1.5, x = 8[/tex]

Answer :

To solve for the values of [tex]\( x \)[/tex] where [tex]\( f(x) = 15 \)[/tex] for the function [tex]\( f(x) = 4|x-5| + 3 \)[/tex], follow these steps:

1. Set up the equation:
We want to find the values of [tex]\( x \)[/tex] such that:
[tex]\[
4|x-5| + 3 = 15
\][/tex]

2. Isolate the absolute value expression:
Subtract 3 from both sides:
[tex]\[
4|x-5| = 12
\][/tex]

3. Solve for the absolute value expression:
Divide both sides by 4:
[tex]\[
|x-5| = 3
\][/tex]

4. Solve for [tex]\( x \)[/tex] using the definition of absolute value:
The equation [tex]\( |x-5| = 3 \)[/tex] can be split into two separate equations:

- Case 1: [tex]\( x-5 = 3 \)[/tex]
Solving this gives:
[tex]\[ x = 3 + 5 = 8 \][/tex]

- Case 2: [tex]\( x-5 = -3 \)[/tex]
Solving this gives:
[tex]\[ x = -3 + 5 = 2 \][/tex]

5. Check the solutions in the context of the problem:
Both [tex]\( x = 8 \)[/tex] and [tex]\( x = 2 \)[/tex] are solutions that satisfy [tex]\( f(x) = 15 \)[/tex].

Thus, the values of [tex]\( x \)[/tex] for which [tex]\( f(x) = 15 \)[/tex] are [tex]\( x = 2 \)[/tex] and [tex]\( x = 8 \)[/tex]. Therefore, the correct answer is:

[tex]\( x = 2, x = 8 \)[/tex]