如何推导：St/(t^2+1)dt=1/2*S1/(t^2+1)d(t^2+1)

Question

如何推导：St/(t^2+1)dt =1/2*S1/(t^2+1)d(t^2 +1)

Answer 1

d(t²+1)=2tdt
所以tdt=1/2d(t²+1)
所以St/(t²+1)dt =1/2*S/(t²+1)d(t² +1)