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 = 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 :

We are given the function

[tex]$$
f(x) = 4|x-5| + 3,
$$[/tex]

and we wish to find all values of [tex]$x$[/tex] such that

[tex]$$
f(x) = 15.
$$[/tex]

Step 1. Set up the equation:

[tex]$$
4|x-5| + 3 = 15.
$$[/tex]

Step 2. Isolate the absolute value term:

Subtract [tex]$3$[/tex] from both sides:

[tex]$$
4|x-5| = 15 - 3 = 12.
$$[/tex]

Then, divide both sides by [tex]$4$[/tex]:

[tex]$$
|x-5| = \frac{12}{4} = 3.
$$[/tex]

Step 3. Solve the absolute value equation:

An equation of the form

[tex]$$
|x-5| = 3
$$[/tex]

has two cases:

1. Case 1: [tex]$x - 5 = 3$[/tex]

Add [tex]$5$[/tex] to both sides:

[tex]$$
x = 3 + 5 = 8.
$$[/tex]

2. Case 2: [tex]$x - 5 = -3$[/tex]

Add [tex]$5$[/tex] to both sides:

[tex]$$
x = -3 + 5 = 2.
$$[/tex]

Conclusion:

The values of [tex]$x$[/tex] for which [tex]$f(x) = 15$[/tex] are

[tex]$$
x = 2 \quad \text{and} \quad x = 8.
$$[/tex]

Thus, the correct answer is: [tex]$x=2, x=8$[/tex].