Hello!!!I hope you can help me at this exercise:

Draw some contour curves in the (x, y)–plane of the function h(x,y)=(a*(x+y))/(x^2+y^2+a^2).

I fixed and the plot can be seen here:(2*(x+y))/(x^2+y^2+4) - Wolfram|Alpha.

But....how is the plot for any ???