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    • Thread Starter

    Hi All

    Please help a returning mature student...
    Help needed with 2 Differentiation Questions.

    Q= 2e^x + e^-2x
    A= 2e^x + -2e^-2x

    Why would they keep 2e^x in the answer ?
    I do understand the -2e^-2x part though managed to work that one out correctly..

    Q= sin(-8Q) the Q is supposed to be theta dont know how to write it on keyboard.
    A= I would tend to give -8 Cos -8Q but the actual answer is
    -8Cos(-8Q)=-8Cos 8Q. So I dont understand how they come to that please help.

    Kind regards

    First one: why not? e^x differentiates to e^x, so 2e^x differentiates to 2e^x.

    Second one: cos is an even function, i.e. cos(-x) = cos x (so in this case, cos(-8Q) = cos(8Q)
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