This may be a silly problem to be having but i've had a couple of year off from uni maths and have forgotten some things i should know but aren't covered in current courseany help would be greatly appreciated cheers,

Question i'm doing off a practice sheet;

Let f:$\displaystyle R^2$--> R be defined by f(x1,x2) = (x1)^2 + (x2)^2

Prove that, lim(x->0) f(x) = 0.

The difficulty i'm having is with the mapping.. i realise that the function maps 2 dimensional vector space to 1d but i'm having trouble understanding the effects this has on the question, i'm good with the epsilon delta in the actual finding of limit but don't think i understand the mapping of the function correctly.. any help would be greatly appreciated cheers.