Hint: For every there exists (unique)
I'm guessing you mean the cube root of (x-5) and you mean the natural domain. What you need to ask yourself is there a problem with cube rooting an number. Well, unlike the square function, the cube function can produce negatives so indeed there is no problem with setting the domain as the real set. As for the range, pick a real number and you want to find a real which maps to it. Easy, cube the former so every real can be mapped to