1. The problem statement, all variables and given/known data Stumped. Integral: f(x,y) = ∫ (from 1 to xy) of e^(t^2)dt find both fx and fy 3. The attempt at a solution I've come up with: fx(x,y) = ∂/∂x ∫ (from 1 to xy) of e^(t^2)dt Not sure where to go... possibly take the integral, the take the partial derivative? I found a solution that moves the derivative into the integral. It just looks like magic to me... not sure what they did. Could someone please break it down for me?