Help with Calc. problem ($5.00 Paypal reward)

[LostHiWay]

I really, really suck at Calc. and need some help with this problem.

I have a function and need to reduce it so I only have x variables. Here's the function

c(x) = (360/(x/n))*(r) + (360/(x/n))*[sx+s(x-n)+s(x-2n)+s(x-3n)+s(x-((x/n)-1)n)]

What I have to do is get it down to only x variables then minimize it...which I should be able to do if someone can help me get it down to only x variables.

Any help??? $5.00 paypal reward

 

[eLiu]

Uh...how do you propose to get rid of r and n? There are no other functions to define those two vars...unless I'm missing something? I would minimize and call n and r arbitrary constants.

 

[datalink7]

42

 

[LordSnailz]

yeah, the question is stated in correctly, there is no way to get rid of r and n unless 1. r and n are constants or 2. there are more eqs. to help you solve this problem.

 

[LostHiWay]

Originally posted by: eLiu
Uh...how do you propose to get rid of r and n? There are no other functions to define those two vars...unless I'm missing something? I would minimize and call n and r arbitrary constants.

I kinda understand what you're saying. I need to take the derivative of that function and I have no clue how to do that unless it only has one variable in it. (instead of 3)

As you can see I'm only calc 1 (and suck at it)

 

[mithrandir2001]

[5x+5(x-n)+5(x-2n)+5(x-3n)+5(x-((x/n)-1)n)]

can be reduced to

[20x-25n]

 

[her209]

c(x) = 360nr/x+(360n/x)*(5x+5x-5n+5x-10n+5x-15n+5x-5x+5n)
= 360nr/x + (360n/x)*(20x-25n)
= (360n/x)*(r + 20x - 24n)

 

[eLiu]

Originally posted by: LostHiWay

Originally posted by: eLiu
Uh...how do you propose to get rid of r and n? There are no other functions to define those two vars...unless I'm missing something? I would minimize and call n and r arbitrary constants.

I kinda understand what you're saying. I need to take the derivative of that function and I have no clue how to do that unless it only has one variable in it. (instead of 3)

As you can see I'm only calc 1 (and suck at it)

Ah, i gotcha. Ok, n and r are constants...just like 1, 2, 3, or any other number. e.g. derivative of x^2 is 2x...2x^2 is 4x, nx^2 is 2nx; like the derivative of any number, deriv n is 0. You just treat it like a regular number; don't differentiate it. Does that make sense?

 

[LostHiWay]

Dammit...I must have read my writing wrong. actually all the 5's were suppose to be s's so the function is:

c(x) = (360/(x/n))*(r) + (360/(x/n))*[sx+s(x-n)+s(x-2n)+s(x-3n)+s(x-((x/n)-1)n)]


So how could I reduce that?

 

[her209]

Originally posted by: her209
c(x) = 360nr/x+(360n/x)*(5x+5x-5n+5x-10n+5x-15n+5x-5x+5n)
= 360nr/x + (360n/x)*(20x-25n)
= (360n/x)*(r + 20x - 25n)

So then it would be:

(360n/x)*(r+4sx-5nx)

 

[MacBaine]

If X is the only variable, then you can simplify it that way, but if all the other letters are variables as well (which I think r and s are), then you would have to take the derivative implicitly.

 

[MacBaine]

Originally posted by: LostHiWay
Dammit...I must have read my writing wrong. actually all the 5's were suppose to be s's so the function is:

c(x) = (360/(x/n))*(r) + (360/(x/n))*[sx+s(x-n)+s(x-2n)+s(x-3n)+s(x-((x/n)-1)n)]


So how could I reduce that?

Factor out the (360/(x/n)) to start with, and then factor out an 'S' from every term of the second part, at which point you can combine all the X's and N's to get...

(360/(x/n))*(r+s(4x-7n))

Pretty sure that's as far as you can go. You can take the derivative with this, as messy as it may get. Use quotient/product rule, and find out if the r, s, and n are constants or not.