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March 1st, 2017, 01:43 PM  #1 
Member Joined: Jan 2014 Posts: 42 Thanks: 0  Derivative of Trig and Euler's number
I have a problem I am having touble solving (refer to image question 1 b). I cannot find any tutorial explaining how to solve Trig and e^x derivatives together. I'm a little rusty with my math, so if anyone could please provide a step by step solution that would be great. I understand the derivative of e^x = e^x & cosx is sinx. But I'm not sure how to get the solution: (e^4t)(80 cos 50t + 1000 sin 50t) μC Thanks. Last edited by skipjack; March 1st, 2017 at 03:10 PM. 
March 1st, 2017, 02:15 PM  #2 
Math Team Joined: Dec 2013 From: Colombia Posts: 7,671 Thanks: 2651 Math Focus: Mainly analysis and algebra 
The product rule for differentiation says $$\frac{\mathrm d}{\mathrm dx}(uv) = v\frac{\mathrm du}{\mathrm dx} + u\frac{\mathrm dv}{\mathrm dx}$$ for functions $u(x)$ and $v(x)$. 
March 1st, 2017, 02:39 PM  #3 
Member Joined: Jan 2014 Posts: 42 Thanks: 0  Thank you
Ahh yes, that's right. I will try and solve now. Thanks.
Last edited by skipjack; March 1st, 2017 at 03:10 PM. 
March 1st, 2017, 03:42 PM  #4 
Member Joined: Jan 2014 Posts: 42 Thanks: 0  problem with answer
Ok I am missing something here, I am getting an inverse answer: hope you can make sense of my answer haha. 
March 1st, 2017, 04:07 PM  #5 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,264 Thanks: 902 
I don't know what you man by "inverse answer". What you give, , is the correct answer.

March 1st, 2017, 05:01 PM  #6 
Member Joined: Jan 2014 Posts: 42 Thanks: 0 
sorry I didn't not see the '' symbol in front of the answer I posted in my first post. Thanks for your help 

Tags 
derivative, derivitive, euler, eulers, number, trig 
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