2)= ∫(3dx/cos^2x)- ∫2cosxdx=3tgx-2sinx+C;
3)= ∫x^(-2)dx- ∫x^(-4)dx=x^(-1)/(-1) - x^(-3)/(-3)+C=
=(-1/x)+(1/(3x^3))+C;
4)=2arctgx+C;
5)= ∫x^((-2/3)-(1/3))dx- ∫x^(-1/3)dx=∫(dx/x)- ∫x^(-1/3)dx=ln|x|-x^(2/3)/(2/3)+C=ln|x|-(3/2)*∛(x^2)+C;
6)=(x^2/2)-arcsinx+2x+C.