Talk:Summation of Grandi's series

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