Question

i need help finding derivatives

Answer 1

\[f(x)=xe^{-9x}\]

Answer 2

i need to find 3 derivatives

Answer 3

what do you mean by find 3 derivatives?

Answer 4

f' f'' and f'''

Answer 5

so? go ahead, f'=?? product rule

Answer 6

\[-9x*e^{-9x}\]

Answer 7

i mean -9 e^-9x

Answer 8

\(f'(x) = x'*e^{-9x}+x (e^{-9x})' = e^{-9x} -9xe^{-9x}\)

Answer 9

does that = \[e^{-9x}(x-9)\]

Answer 10

F'=(1-9x)*e^-9x

Answer 11

check again, my answer is ok:)

Answer 12

f'' =
\[(x-1)(1-9x)e^{-9x}\]

Answer 13

Please, tell me whether you get f' yet? and DON'T factor, it turns very complicated next in next steps

Answer 14

I understand now that (1-9x)e^{-9x}= f'

Answer 15

Don't factor, please.

Answer 16

\(f'(x) = x'*e^{-9x}+x (e^{-9x})' = e^{-9x} -9xe^{-9x}\)
\(f''(x) = (e^{-9x} -9xe^{-9x})'\)

Answer 17

this is why i am so confused.. the factoring part is too much

Answer 18

It's ok when factoring, but why do we make the life harder by product rule again for f" ?
now, just take derivative term by term and the second term is exactly what we did for f' * (-9) ,right?

Answer 19

\(f''(x) = (e^{-9x})' -9(xe^{-9x})'\)