I ended up with 9/8xsin(8x)-9/8sin(8x) and am not sure what am i missing. On a side note, how can I input that problem into Wolfram Mathematica? I tried Integrate[9xCos(8x) dx, x] and it gave me a strange value.
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Originally Posted by masterofcheese I ended up with 9/8xsin(8x)-9/8sin(8x) and am not sure what am i missing. On a side note, how can I input that problem into Wolfram Mathematica? I tried Integrate[9xCos(8x) dx, x] and it gave me a strange value. What method did you use? P.S. Try "integrate 9*x*cos(8*x)"
Oh, sorry, forgot to say, but this is integration by parts.
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