is a function differentiable at the point

Question

$G(x,y)=(x^2+y,xy+x^2)$, $P=(a,b)$ is G differentiable at P? calculate dG(P)

Attempt:

I think I understand how to find dG(P) it is just, $dG(P) = (2a,b)$ correct?

I am needing help how I show that G is differentiable at P.