I pretty much can find the domain ofcertain basic functions.I understand the domain and range in the form of the point (x,y) = (domain, range). However, I just don't comprehend the idea of finding the range of any function.

Here are two questions:

(1) Find the range of f(x) = -(sqrt{-2x + 3})

(2) Find the range of y = -x^4 + 4