1/√a∫(1+4√x)^1/3dx
(1+4√x)=u^3
4√x=u^3-1
x=(u^3-1)^2/16
dx=2(u^3-1)*3u^2du/16=3(u^3-1)u^2du/8
3/8√a∫u(u^3-1)u^2du=3/8√a(u^7/7-u^4/4)=
=3/8√a(((1+4√x)^(7/3))/7-((1+4√x)^(4/3))/4)
