Or are they?

Guys, find the antiderivative of {1/2y dy. There are... two antiderivatives? Those are (1/2)ln(abs(2y)) + C and (1/2)ln(abs(y)) + C. Confused? So am I.

Try solving the differential equation dy/dx = 2y(3-x) twice, using the identical antiderivatives of {1/2y dy = (1/2)ln(abs(2y)) + C and (1/2)ln(abs(y)) + C. I think you'll come up with different answers just like I did lol.

I've another question. Is it possible to find the exact sum of the following series -

-3/(2^2) + 6/(2^5) - 9/(2^8)....