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mathcalculusBest ResponseYou've already chosen the best response.0
okay i understand everything..... except how to find the minimum!
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
are you familiar with derivative?
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
i know they got the equation. y=6x+(21000/x)
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
then after i'm not sure how they got: Minimum occurs at 59.16 ft for the length (found on a graphing calc) width: 10500/59.16 = 177.5 ft Perimeter = 710 ft
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
ok, well the method they got the minimum is just by using a graphing calculator with a max min function on it doing it manually would involve finding the first derivative of the equation and then setting it equal to zero and then solving for L
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
is there a way to do that without it?
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
without the graphing calculator? or without having to do it manually?
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
by hand would involve finding the first derivative of the equation and then setting it equal to zero and then solving for L
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
because the slope at the minimum point is zero
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
im doing it wrong, even on calculator :/ I'm not getting it.
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
\[y = \frac{21000}{x} + 6x\] \[y' = \frac{21000}{x^2} +6\] \[y' =0\] \[0=\frac{21000}{x^2} +6\] solve for x hopefully i didnt screw up the derivative
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
\[\frac{1}{x} = x^{1}\]
 8 months ago

PsymonBest ResponseYou've already chosen the best response.0
@completeidiot derivative is fine :3
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
im just pointing out the identity that allows you to use the "power" rule for derivatives
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
\[y= x^n\] \[y' = nx^{n1}\]
 8 months ago

mathcalculusBest ResponseYou've already chosen the best response.0
im not getting that. i got up to here: y=621000/x^2 then set it to 0
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
1/x is not part of the problem you can ignore it if you want its just that the identity is sometimes not obvious to other people
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
once you set it equal to zero 0=621000/x^2 just solve for x
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
6= 21000/x^2 x^2= 21000/6 x = sqrt {21000/6}
 8 months ago

completeidiotBest ResponseYou've already chosen the best response.2
any other questions? sorry for any confusion i may have caused
 8 months ago
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