For a given function f(x), the operation f(3x) will A) shrink the graph vertically by a factor of 1/3.
B) stretch the graph vertically by a factor of 3.
C) stretch the graph horizontally by a factor of 3.
D) shrink the graph horizontally by a factor of 1/3.

Anytime you have multiplication happening inside the function notation, it will impact the x-values or horizontal aspect of the graph.

This knocks out A and B.

Almost everything that happens inside function notation has the opposite impact on the graph from what you think it would. I see “3 times” and think “oh, that’d make it three times bigger. Nope. It has the opposite result: it will shrink the graph by a factor of 1/3.

D