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# Maths Diff Question confusion Pls help watch

1. Hi All

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

Kind regards
SZia
2. 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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Updated: September 23, 2010
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