I have troubles in working out the range of the following relations:

y=x-a, x<0, a>0

y=(a/x)+a, a>0

May you please list out the steps because I really want to understand the way~

Also:

y=square root x, x>_0 ---> Shouldn't the range be "all real numbers"? I saw the answer is [0,infinity[

(Because for example, assuming that x=81, so y=square root 81, which equals either (-9) or (9), meaning that negative numbers are also accepted, so I think it is "all real numbers") Am I right?