Question

first and second derivative for e^x (cos x)
I'm thinking about it wrong...

Answer 1

f' = chain rule (e^x) and (cos x) are the terms with x so derivative of the first times the second times the derivative of the second, no? .... except e^x and cos x are not inside one another.... they are just separate terms multiplied together....hmmmm

Answer 2

\[f(x)=e^x\cos x\]
\[f'(x)=\frac{d}{dx}[e^x]\cos x+e^x\frac{d}{dx}[\cos x]\\
f'(x)=e^x\cos x-e^x\sin x\\
f'(x)=e^x(\cos x-\sin x)\]
You're thinking of "product rule", not chain rule.

Answer 3

I should be thinking product rule not chain rule...f'g +g'f

Answer 4

oh well there we go I'm back on track

Answer 5

thanks sometimes just need to type things out i guess

Answer 6

No problem