domain is the set of numbers you can use for the equaiton
remember you can't divide by zero, or take the squaer root of a negtive number (we don't have sqrts in this quesiton so don't worry about last one)
so you can't divide by 0
domain =all real number except those that make divide by zero
where is that?
x-1=0
x=1
when x=1, we can't allw that
domain=all real numbers except 1