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mathcalculus
Group Title
mathcalculus
HELP: Determine the values of where the tangent line is horizontal for the function:
 one year ago
 one year ago
mathcalculus Group Title
mathcalculus HELP: Determine the values of where the tangent line is horizontal for the function:
 one year ago
 one year ago

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mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
i know i have to find the derivative and set it to zero but it's not coming out to be correct. can anyone help me
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
so i did 3x^26x4=0
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
i tried to use the quadratic formula and got sqrt(21)+3/3
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
+ or  sqrt(21)+3/3
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
also aka 2.52753...
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
derivative seems correct
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
to find what x = to... ?
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
i used quadratic formula
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
@dumbcow dont i have to do that to find x??
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
im getting it wrong,
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
yes everything looks correct to me...do they want exact or decimal answer?
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
http://www.wolframalpha.com/input/?i=3x%5E26x4%3D0
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
can i use quadratic formula for ths one?
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
@dumbcow
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
????????????????????????
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
yes of course you use quadratic formula...thats how you got your answer that i said looked correct
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
im not getting that using quadratic formula
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
im getting something totally different and wrong
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
\[x = \frac{3 \pm \sqrt{21}}{3}\]
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
yes! but from 6+2*sqrt(21)/6?
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
shouldnt it be 1+ or  sqrt 21/3
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
same thing, just a matter of splitting up fraction or keeping it as single fraction
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
no it's not because the answer is 1+ sqrt (7/3) gives me 2.52753 and 1+sqrt 21/3 gives me 1.86086!
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
@dumbcow
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
hmm \[\frac{\sqrt{7}}{\sqrt{3}} = \frac{\sqrt{21}}{3} \]
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
hmmm?
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
@dumbcow
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
try it on a calculator.
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
http://www.wolframalpha.com/input/?i=1%2Bsqrt%287%2F3%29+%2C+1%2Bsqrt%2821%29%2F3
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
oh you added the "1" before dividing by "3"
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
okay from my answer.... not the internet.. 6+2 sort(21)/3.... where do i go from there?
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
well it should be a 6 on bottom
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
no i didn't add anything.
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
okay sure a 6. i thought it could be a 3 to narrow it down
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
so 6+or2sqrt(21)/6
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
i dont see the problem, you posted answer in beginning... " i tried to use the quadratic formula and got sqrt(21)+3/3 "
 one year ago

mathcalculus Group TitleBest ResponseYou've already chosen the best response.0
so it is a 3 in the denominator!
 one year ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
\[\frac{6 \pm 2\sqrt{21}}{6} = \frac{2(3 \pm \sqrt{21})}{6} = \frac{3 \pm \sqrt{21}}{3}\]
 one year ago
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