Question 158089
The domain is given as all values of x where the function exists. Generally, you look for things that are 'not allowed'. Things like dividing by zero or the square root of a negative number will result in non-real results. So, any value of x that makes things like that happen are excluded from the range.

In the case of {{{y = -2x +1}}} there are no real value of x that result in a non-real value of y. So, the domain is "all x" and the range is 'all y'. That is, there are no invalid answers for this one.

For the other problems you have, look for things like I noted above. If for instance, you are given {{{y = 1/x}}}, then the when x=0, the value for y is undefined. So the domain there would be "all x except 0", and the range would be 'all y'.

For something like {{{y = sqrt(x)}}}, since you can't have a real square root of a negative number, the range would be "all x >= 0". Since square roots can be both negative and poistive, the range is "all y".

Hope this helps