Talk:Summation of Grandi's series

Is the proof through integration valid?
The proof through integration section includes two constants, which, near the end, $$ \int e^{x}\sin x \, dx=Ge^{x}(\sin{x}-\cos x) + C = \frac{e^{x}(\sin{x}-\cos{x})}{2} + C $$ cancel out. Is that kind of step valid? 128.84.126.120 (talk) 22:57, 4 September 2015 (UTC)