Question

what are they doing with the x? x(1-x^2)^4
u=1-x^2
du=-2x
-1/2 du=dx

Answer 1

-1/2 integral u^4 du

Answer 2

you then do u^5/5 but i cant figure out where the extra x is going

Answer 3

You made a typo.

Answer 4

-1/2 du = x dx.

Answer 5

ohh my god. i never understood how to find du when it came with an variable. no wonder. thanks!

Answer 6

No problem :P .