Evaluate ∫1x2+1 dx\displaystyle\int \frac{1}{x^2 + 1}\, dx∫x2+11dx.
arctan(x)+C\arctan(x) + Carctan(x)+C
ln(x2+1)+C\ln(x^2+1) + Cln(x2+1)+C
12arctan(x2)+C\dfrac{1}{2}\arctan(x^2) + C21arctan(x2)+C
sec2(x)+C\sec^2(x) + Csec2(x)+C