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Math Help - Trig derv. problem

  1. #1
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    Trig derv. problem

    Find F'(x)=x2(1 + cos(x))

    Should I dist. the x^2?

    I cannot seem to get started.
    Thanks.
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  2. #2
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    e^(i*pi)'s Avatar
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    Yes you can, then use the product rule on the second term: F'(x) = x^2+x^2 \cos(x). Or you can use the product rule directly with u = x^2 \text{  and  } v = 1+\cos(x). You get the same result.

    Out of interest are you trying to find the second derivative or is F'(x) a typo?
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  3. #3
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    I have a whole gaggle of things I have to do with this problem, and I've been putting it off. But i want to get it done to go to a baseball game(fella watch) tomorrow. Sigh. Responsibility. Would Substitution be easier or should I just buck up and do it?
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  4. #4
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    e^(i*pi)'s Avatar
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    A sub won't help, you'd still have to do the product rule which really isn't that much trouble
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  5. #5
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    so: 2x+2xCos(x)-x^2Sin(x)?
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  6. #6
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by FreaKariDunk View Post
    so: 2x+2xCos(x)-x^2Sin(x)?
    Yes. You can also factor out x to give: x(2-2\cos(x)-x\sin(x))
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  7. #7
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    Just in case FreaKariDunk reads this before e^(pi*i) gets back, factoring out x will actually give: x \left ( 2 + 2\cos{x} - x\sin{x} \right ).
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  8. #8
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    Thank you y'all for all your help. All work and No play makes me grumpy. :P
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