No, I wouldn't go in that direction. I would build up the function f(x) from the simpler components using inequalities, like this:
How could you finish?
Can you help me with the following problem please?
If f(x) = 2 sin(3x - pi/2) + 5, what is the range of the values of f(x)?
I began by moving 5 over to the other side.
2 sin(3x - pi/2) = - 5
sin(3x - pi/2) = -5/2
Am I going in the right direction?