Domain and Range are my weakness. I have attempted these problems but I am not sure that they are correct could someone check them/tell me how to correct them please?

Many thanks!

f(x)=1+(x^2) D: all reals R:[1, inf)

f(x)=1-(1/x) D: (-inf, 0) R: (0, inf)

f(x)=sqrt(3x-1) D: (1/3, inf) R: (1/3, inf)

f(x)=(x^3)-8 D: all reals R: all reals

f(x)=x/(x-3) D: (-inf, 3) R: (3, inf)

Also, if i wanted to write the domain as all reals except one do i denote thatR-1?