The function f is defined by f(x)=(2x^2)-5. What are all possible values of f(x) where -2<x<2?
I don’t understand how to do this.

Easiest way is probably to graph it.

The vertical dashed lines are x = –2 and x = 2. Between those lines, you care about all the values of f(x), which basically means you care about all the y-values. That’s everything from y = –5 to y = 3, inclusive.