Paper 2, Section I, E

Analysis II
Part IB, 2019

Consider the map f:R2R2f: \mathbb{R}^{2} \rightarrow \mathbb{R}^{2} given by

f(x,y)=(x1/3+y2,y5)f(x, y)=\left(x^{1 / 3}+y^{2}, y^{5}\right)

where x1/3x^{1 / 3} denotes the unique real cube root of xRx \in \mathbb{R}.

(a) At what points is ff continuously differentiable? Calculate its derivative there.

(b) Show that ff has a local differentiable inverse near any (x,y)(x, y) with xy0x y \neq 0.

You should justify your answers, stating accurately any results that you require.