Question

∫dx/x（x²-1）^½

Answer 1

∫dx/[x√(x^2-1)]

let
x=secy
dx=secytanydy

∫dx/[x√(x^2-1)]
=∫dy
=y+C

=arcsecx + C

追问

那个，答案不对啊，答案是arccos（1/|x|）+c

追答

=arcsecx + C
=arccos(1/|x|) + C

x=secy
1/x = cosy
y = arccos (1/x)