Derivative of (3/(5t)-1)/((2/t^2)+7)? Answer in the book is: (-21t^2 - 20t + 6)/(5(2 + 7t^2)^2 I don't know what is going on with my math, but I can't seem to get this right :[ Here are my fail attempts : 1. http://puu.sh/4FyMW.JPG 2. http://puu.sh/4FyTA.JPG
you cannot multiply and divide by different quantities (5t and t^2) start by multiplying and dividing by 5t^2
yeah i knew that, but i tried it anyways to see what would happen haha. but in the 1st picture, i felt like i was on the right track, but i don't know anymore
in 1st pic , you took the derivative of numerator and denominator separately ? instead of using quotient rule ? thats not allowed
yes, don't you need the derivative of the numerator and denominator to use the quotient rule?
let me check again
(3/5*t^(-1)-1)/(2t^(-2)+7) d(u/v)/dt=(u'v-v'u)/v^2 u'v=-1(3/5)t^(-2)*v uv'=-4t^(-3)*u That should get you started.
mmk i'm gonna try that
easier thing to do is to multiply and divide by 5t^2
i'm making this so complicated for myself :( i'll try what you said by multiplying and dividing by 5t^2 instead
sorry that took so long. for some reason, the 5's cancelled out at the end
oh nvm, i see the problem. oops~ thx guys :D
oh, so you got it now ?
yeah. too tired to think at this time. i'm not noticing all these little things
thats where the error lies
you have only written 5(....)^2
eheh. can't believe i spent 41 mins on a one math problems :(
if its any consolation, i have, many times spent 7-8 hours on one problem :P
lol xD. good night! i think i need it
sure, have a sound sleep and sweet dreams :)
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