Posted by Soroban on August 04, 2002 at 01:53:35:
In Reply to: antiderivatives and trig. functions posted by Wally on August 03, 2002 at 17:21:53:
: If I intergate x cos x dx it = xsinx + cosx + c
: I think you use the product rule to work this problem but i come up with an answer of xsinx + cos x x^2/2
Sorry, Wally. There is NO "Product Rule" for integrals!
: What is the correct way to work this problem. I'm not sure why you don't have g(x).f' on the second part of the product rule.
If you're integrating, why do you have f' (a derivative)?
Try integrating "by parts": u = x, dv = cos x dx.
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