The integral ∫0x11+t2 dt\int_0^x \frac{1}{1+t^2} \, dt∫0x1+t21dt can be expressed as a power series ∑n=0∞(−1)nx2n+12n+1\sum_{n=0}^{\infty} \frac{(-1)^n x^{2n+1}}{2n+1}∑n=0∞2n+1(−1)nx2n+1. This integral equals:
ln(1+x2)\ln(1+x^2)ln(1+x2)
arctan(x)\arctan(x)arctan(x)
arcsin(x)\arcsin(x)arcsin(x)
11+x\frac{1}{1+x}1+x1