1ãâ«(0,Ï/2) cos^6xdx
=â«(0,Ï/2) cos^5xd(sinx)
=cos^5xsinx|(0,Ï/2)+â«(0,Ï/2) 5sin^2xcos^4xdx
=â«(0,Ï/2) 5(1-cos^2x)cos^4xdx
=5â«(0,Ï/2) cos^4xdx-5â«(0,Ï/2) cos^6xdx
â«(0,Ï/2) cos^6xdx=(5/6)*â«(0,Ï/2) cos^4xdx
=(5/6)*(3/4)*â«(0,Ï/2) cos^2xdx
=(5/6)*(3/4)*(1/2)*â«(0,Ï/2) dx
=(5/6)*(3/4)*(1/2)*(Ï/2)
=5Ï/32
2ãâ«(0,1) f(x)/âxdx
=â«(0,1) (1/âx)dxâ«(1,âx)e^(-t^2)dt
=-â«(0,1) (1/âx)dxâ«(âx,1)e^(-t^2)dt
=-â«(0,1) e^(-t^2)dtâ«(0,t^2)1/âxdx
=-â«(0,1) e^(-t^2)dt*2âx|(0,t^2)
=-â«(0,1) 2te^(-t^2)dt
=â«(0,1) e^(-t^2)d(-t^2)
=e^(-t^2)|(0,1)
=1/e-1
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