ANSWER
f(3x)
f(6x) + 9
EXPLANATION
A function is said to undergo horizontal compression if it changes as follows:
[tex]\begin{gathered} f(x)\Rightarrow\text{ f(bx)} \\ \text{given that b > 1} \end{gathered}[/tex]
This means that the functions that include a horizontal compressions are functions that have that form of transformation in them.
Note: b must be greater than 1
Therefore, the correct options are:
f(3x)
f(6x) + 9
