Can someone explain domain and range to me? I recall doing these problems this past year, but since all textbooks were turned in in May, I have no point of reference for my summer homework, and my memory is a little foggy.

The first problem says find the domain of the function: f(x)= (square root of (x-5))/(x^2-6x+8)

The other problem says find the domain and range of the funtion:

f(x)=(4/5)l8-xl

A refresher course in domain and range would be helpful.