A. The Jacobian for the transformation
[tex]\begin{cases}x=\dfrac{40}{41}u-\dfrac9{41}v\\\\y=\dfrac9{41}u+\dfrac{40}{41}v\end{cases}[/tex]
is
[tex]\dfrac{\partial(x,y)}{\partial(u,v)}=\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}\dfrac{40}{41}&-\dfrac9{41}\\\\\dfrac9{41}&\dfrac{40}{41}\end{bmatrix}[/tex]
B. This question seems to be incomplete...