I have the following integral $$\int_0^1 \int_0^1 \frac{xdxdy}{x^2 + y^2} $$
I first took the partial integral with respect to y to obtain the following: $$ \left [ \frac{1}{x} \tan^{-1}x \frac{y}{x} \right ]_{y = 0}^{y = 1} \rightarrow \int_0^1 \frac{1}{x} \tan^{-1}x \, dx \ \text{(now taking partial integral with respect to x)} $$ I try u substitution next but I get stuck.
Also is $$\int_0^1 \int_0^1 \frac{xdydx}{x^2 + y^2} = \int_0^1 \int_0^1 \frac{xdxdy}{x^2 + y^2} ?$$ by Fubuni's Theorem