1)find derivative of u wrt to x and then wrt y 2)show that (x times derivative of u wrt x)+(y times derivative of u wrt y) = u +2x
du/dx = x(2x)/(x^2+y^2) +ln(x^2+y^2) -2 y(-y/x^2)(1/(y^2/x^2)) + 0 because dy=0 this time That should get you started. I am not going to plod through the whole thing.
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