- #1

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I DONT KNOW WHAT TO DO.....

I started off by doing the derivative of the first equation, which was a guess but then what I do?

- Thread starter thomasrules
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- #1

- 243

- 0

I DONT KNOW WHAT TO DO.....

I started off by doing the derivative of the first equation, which was a guess but then what I do?

- #2

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- #3

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k i've got 0= -0.01+(15)x^-1+(625)x^-2

NOW WHAT....how to find x

NOW WHAT....how to find x

- #4

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[tex] \frac{dU}{dx} = \frac{-625}{x^2} + 0.01 [/tex]. Now solve for x.

- #5

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dude what happened to the 15x^-1 !!!!!

- #6

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One thing you have to be careful about; when you set [tex]\frac{dU}{dx}=0[/tex] you are looking for maximuns and minimums, you might also need to do a 2nd Derivative test to find out which one it is.

- #7

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Then I did what you suggested ryoukomaru and did the second derivative of that.

I got 0= -15x^-2-1250x^-3

I HATE THIS PLEASE HELP

- #8

HallsofIvy

Science Advisor

Homework Helper

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C(x)/x= 625/x+ 15+ 0.01x

The derivative of 625/x= 625x

The derivative of 15, a constant, is

The derivative of 0.01x

The derivative of C(x)/x= -625

- #9

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k thanks i got it

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