Question

Find the jacobian of the transformation. x = u2 + uv, y = uv2

Answer 1

$\mathbf J=\begin{bmatrix}\dfrac{\partial x}{\partial u}&\dfrac{\partial x}{\partial v}\\\\\dfrac{\partial y}{\partial u}&\dfrac{\partial y}{\partial v}\end{bmatrix}=\begin{bmatrix}2u+v&u\\v^2&2uv\end{bmatrix}$

The Jacobian has determinant

$\det\mathbf J=\begin{vmatrix}2u+v&u\\v^2&2uv\end{vmatrix}=(2u+v)2uv-uv^2=4u^2v+uv^2=uv(4u+v)$