Here's the question you clicked on:
Staffy
Solve (∂^2u/∂x^2) + (∂^2u/∂y^2) = 0 in y > 0 and −∞ < x < ∞ with u(x, 0) = f(x).
Is this Calc or Diff eq?
I'm willing to work through this with you. A reply would be nice.
It's differential equations, it's for a mathematical physics class
the classic example of \(\displaystyle \frac{\partial^2 u }{\partial x^2}+\frac{\partial^2 u }{\partial y^2}=0\) is \(\displaystyle u(x,y)=e^x \cos y + e^y \sin y\)
Sorry, I should specify that we are using fourier transforms to solve these problems