(x,y)
to be a function
for every x, ther must be only 1 y to corespond to it
basically, x must NEVER repeat with a different y
list them
ah, we see (1,1) an d(1,-1)
also (4,2) and (4,-2)
double offense
1 repeats with 1 and -1
4 repeats with 2 and -2
not a function
domain is all x values
range is all y values
if they repeat, don't list them
domain=(0,1,4)
range=(-2,-1,0,1,2)
