∫x/(1+√1+x^2)dx

∫x/(1+√1+x^2)dx


∫ln(x+√(1+x^2))dx
=xln(x+√(1+x^2)-∫xd(ln(x+√(1+x^2))
[ln(x+√1+x^2)]'=[1+x/√(1+x^2)]/(x+√(1+x^2))=1/√(1+x^2)
=xln(x+√(1+x^2)-∫xdx/√(1+x^2)
=xln(x+√(1+x^2)-(1/2)∫d(1+x^2)/√(1+x^2)
=xln(x+√(1+x^2)-√(1+x^2)+C



∫x/(1+X^2)dx=


=1/2∫1/(1+x^2)d(1+x^2)
=1/2 ln(1+x^2)+c



∫1/〔x(X^2-1)〕dX=


let
x= secy
dx=secy tany dy
∫1/[x(x^2-1)] dx
=∫coty dy
=ln|siny| + C
=ln|√(x^2-1)/x | + C