Calculus/Derivative

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Expert: - 6/8/2009


Question
I'm trying to find the derivative of y=cos(e^-3x).  I have the first line: y'=-sin(e^-3x)(e^-3x)(-3), But I'm not sure where to go from there.

Answer
All that can be done is the terms reorderd.
It is common to put constants out in front.  
Note that the product of two negatives is a positive when this is done.  This means we have y' = 3sin(e^-3x)(e^-3x).

It is also good practice to put negative exponent in the denominator as positive exponets.

This makes it y' = 3sin(e^-3x)/(e^3x).

If there was no negative in the exponet, it is common to leave the function the way it was since trig functions are often written last.

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