Question

f(x)=e^-5x cos3x find f '(x)

Answer 1

I know that -5e^-5x from there am kind of lost

Answer 2

So this is a product rule derivative. We need f'(x)g(x) + f(x)g'(x) where e^-5x will be f(x) and cos3x will be g(x) So first, the derivative of e^-5x is -5e^-5x and the derivative of cos3x is -3sin3x. So now using those two derivatives and plugging them into the product rule formula, we have -5e^-5x cos3x - 3e^-5x sin3x

Answer 3

I see that there is really no way to simplify the answer or is it? -8e^-5xcos3xsin3x?

Answer 4

Well, you cannot do too much to simplify. Depends on how much simplification is necessary. Really, you could only factor out an e^-5x to get e^-5x(-5cos3x - 3sin3x)

Answer 5

thank you!

Answer 6

Np ^_^