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Math Help - Quotient rule question.

  1. #1
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    Quotient rule question.

    If y = (x^2 + 3x)cosx , find the value of dy/dx when x=0
    Can someone show me how to do this q please.
    Thanks
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  2. #2
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    Quote Originally Posted by Detanon View Post
    If y = (x^2 + 3x)cosx , find the value of dy/dx when x=0
    Can someone show me how to do this q please.
    Thanks
    Quotient Rule? You'd be much better off with the Product Rule since we're not doing any division here.


    The product rule is \dfrac{dy}{dx} \left[u(x)v(x)\right] = v\dfrac{du}{dx} + u\dfrac{dv}{dx}



    In your case u = x^2 +3x and v = \cos(x)


    Once you've differentiated find y'(0). For reference I get an answer of 3
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