High School

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

Answer :

Let's solve the problem step-by-step to find the values of [tex]\( x \)[/tex] for which [tex]\( f(x) = 15 \)[/tex] given the function [tex]\( f(x) = 4|x-5| + 3 \)[/tex].

1. Set the function equal to 15:
[tex]\[
4|x-5| + 3 = 15
\][/tex]

2. Isolate the absolute value expression:
[tex]\[
4|x-5| = 15 - 3
\][/tex]
[tex]\[
4|x-5| = 12
\][/tex]

3. Solve for the absolute value:
[tex]\[
|x-5| = \frac{12}{4}
\][/tex]
[tex]\[
|x-5| = 3
\][/tex]

4. Remove the absolute value by setting up two equations:
- Case 1: [tex]\( x-5 = 3 \)[/tex]
- Case 2: [tex]\( x-5 = -3 \)[/tex]

5. Solve each case:
- Case 1:
[tex]\[
x - 5 = 3
\][/tex]
[tex]\[
x = 3 + 5
\][/tex]
[tex]\[
x = 8
\][/tex]

- Case 2:
[tex]\[
x - 5 = -3
\][/tex]
[tex]\[
x = -3 + 5
\][/tex]
[tex]\[
x = 2
\][/tex]

6. Conclusion:
The solutions are [tex]\( x = 2 \)[/tex] and [tex]\( x = 8 \)[/tex].

Therefore, the answer is [tex]\( x = 2, x = 8 \)[/tex].