∫14+x2 dx=\displaystyle\int \dfrac{1}{4 + x^2}\,dx =∫4+x21dx=A14+x2+C\dfrac{1}{4 + x^2} + C4+x21+CB12arctan(x/2)+C\dfrac{1}{2}\arctan(x/2) + C21arctan(x/2)+Ccheck_circleC14arctanx+C\dfrac{1}{4}\arctan x + C41arctanx+CDarctan(x/2)+C\arctan(x/2) + Carctan(x/2)+CExplanationPattern 1/(a2+x2)1/(a^2 + x^2)1/(a2+x2): antiderivative (1/a)arctan(x/a)(1/a)\arctan(x/a)(1/a)arctan(x/a).