Question

积分，哪位大神帮忙算算，忘完了！

Answer 1

let
x=d.tanu
dx=d.(secu)^2 du
∫ dx/(x^2+d^2)^(3/2)
=∫ d.(secu)^2 du/ (dsecu)^3
=(1/d^2)∫ cosu du
=(1/d^2) sinu + C
=(1/d^2) [x/√(x^2+d^2)] + C