1. The problem statement, all variables and given/known data f(x,y) = exp(-x^2 +xy -y^2) transform with x =(1/sqrt(2)) *(u – v), y = (1/sqrt(2))* (u + v) . 2. Relevant equations Jacobian 3. The attempt at a solution Jacobian = 1 f(u,v) = exp(-(u^2)/2 -(3v^2/2) double integral f(u,v) du dv the bounds would be x > 0 => ( u-v) >0 => u > v and x < ∞ => u < ∞ v > 0 to v < ∞ I am lost on what to do next. If anyone can be as kind as to help, I would greatly appreciate it!