The question asks for the function that represents values given in a table. In function notation, the number inside the parentheses is the \( x \)-value that goes into the function, or the input, and the value that comes out of the function is the \( y \)-value, or the output. Together, they represent points on the graph of the function.
The table shows pairs of values for \( x \) and \( f(x) \), and the correct function must work for every point on the graph. Plug in values from the table and eliminate functions that don’t work. Try the point \( (0, 15) \) and plug \( x = 0 \) and \( f(x) = 15 \) into the answer choices:
* Choice (A) becomes \( 15 = 3(0) + 12 \), or \( 15 = 12 \). This is not true, so eliminate (A).
* Choice (B) becomes \( 15 = 3(0) + 15 \), or \( 15 = 15 \). This is true, so keep (B), but check the remaining answers just in case.
* Choice (C) becomes \( 15 = 15(0) + 12 \), or \( 15 = 12 \); eliminate (C).
* Choice (D) becomes \( 15 = 15(0) + 15 \), or \( 15 = 15 \); keep (D).
Two answers worked for the first point, so try a second point from the table and plug \( x = 1 \) and \( f(x) = 18 \) into the remaining answers:
* Choice (B) becomes \( 18 = 3(1) + 15 \), or \( 18 = 18 \); keep (B).
* Choice (D) becomes \( 18 = 15(1) + 15 \), or \( 18 = 30 \); eliminate (D).
The correct answer is (B).