If y = x²/1+x², ∫ y dx = C + f, f = ______?

x - 1 + 1/(x+1)

x + 1 + 1/(x+1)

x - 1 + 1/(x-1)

None of these

Given y = x²/(1 + x²),

∫y dx = ∫[x²/(1 + x²)] dx = ∫[1 - 1/(1 + x²)] dx = x - arctan(x) + C.

Given ∫y dx = C + f, f = x - arctan(x).

x - 1 + 1/(x + 1)