help haya with maths thread (1 Viewer)

hayabusaboston · Apr 2, 2017

hey folks! switched career paths from med focus to maths focus, started maths this sem after 3 years lol.

will post q's, any help appreciated

1. find 8th derivative of exp(-sqrt3t).sint

i got 2^7.sqrt3(exp(-sqrt3t)sint)

am i right?

He-Mann · Apr 10, 2017

I'd like to see your working, otherwise wolframalpha can easily answer your question.

I'm highly skeptical of that answer due to it's simplicity and given this:

$\begin{align*} y = e^{-\sqrt{3t}}\sin t \Rightarrow \ln y &= -\sqrt{3t} + \ln( \sin t) \\ \Rightarrow \frac{dy}{dt} \frac{1}{y} &= -\frac{3}{2\sqrt{3t}} + \cot t \\\Rightarrow \frac{dy}{dt} &= \left( -\frac{3}{2\sqrt{3t}} + \cot t \right )(e^{-\sqrt{3t}}\sin t)\end{align*}$

which yields more doubt.

help haya with maths thread (1 Viewer)

hayabusaboston

Well-Known Member

He-Mann

Vexed?

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