integration by parts (1 Viewer)

[watatank]

hey i was wondering if anyone could help me out with integration by parts?

I [y³.e^-y/2 dy] limits: 0--> infinity

thanks

 

[Slidey]

Integrate the exponential so that eventually y^3 becomes a constant:
=[-2y^3.e^(-y/2)] + 6*Int y^2.e^(-y/2) dy

Int y^2.e^(-y/2) dy
= [-2y^2.e^(-y/2)] + 4*Int y.e^(-y/2) dy

Int y.e^(-y/2) dy
= [-2y.e^(-y/2)] + 2*Int e^(-y/2) dy
= [-2y.e^(-y/2)] + [-4e^(-y/2)]

Now just add them all together.

BTW, I don't think 4unit integrals have limits to infinity.

 

[watatank]

sweet...thanks heaps man

 

[Slidey]

No problem.