Question

integrate x cos x dx

u=x and du=dx and that helps me how exactly?

Answer 1

integration by parts problem
uv - integral(vdu)

Answer 2

so you are saying the person who suggested substitution was sending me on a wild goose chase? arrrrrgh

Answer 3

you cannot do substitution here, if you substitution cosine, there is no sine in the function to make it equivalent and cancel out with u

Answer 4

I'll give parts a try.......Ultra Violet kills Voo Doo uv- int vdu

brb