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**kdria041****Member**- Registered: 2005-12-27
- Posts: 4

0 0

1 0

2 0

3 10

4 83

5 170

6 300

7 500

8 750

9 1150

10 1500

11 1750

12 1800

Can anyone give me the formula for this plot? The numbers are not absolute, as they were taken off a small graph, so a formula that would aproximate this curve is ok. THANKS!

asympyotes 0, 1800

This is the curve for which I need an equation:

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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

Here is a silly answer that uses operators that are probably disallowed in algebra in this fashion for some reason or other.

y=0(x<3) + (3 ≤ x<11)(1800/(11-3))(x-3) + (x ≥ 11)1800

**igloo** **myrtilles** **fourmis**

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**MathsIsFun****Administrator**- Registered: 2005-01-21
- Posts: 7,582

The tanh(x) function has two horizontal asymptotes, it could be adapted possibly.

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,905

arctan(x) also has two horizontal asymptotes.

But I think that these functions cannot be adapted for this graph, because it is not symmetric.

IPBLE: Increasing Performance By Lowering Expectations.

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**mathsyperson****Moderator**- Registered: 2005-06-22
- Posts: 4,900

kdria041 wrote:

Why not this for solution?:

if:3<x<12 y=((1/logx^3)+1)*x^3

kdria posted that meaning to reply to this topic, but accidentally starting a new one instead.

You can reply using the 'post reply' button. ;)

Why did the vector cross the road?

It wanted to be normal.

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**seerj****Member**- Registered: 2005-12-21
- Posts: 42

krassi_holmz wrote:

arctan(x) also has two horizontal asymptotes.

But I think that these functions cannot be adapted for this graph, because it is not symmetric.

Yes I quote him! You can use arctan(x) by creating your own function

For example try to plot a function like this:

2*atan(x-3)+3

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**seerj****Member**- Registered: 2005-12-21
- Posts: 42

seerj wrote:

krassi_holmz wrote:

But I think that these functions cannot be adapted for this graph, because it is not symmetric.Yes I quote him! You can use arctan(x) by creating your own function

For example try to plot a function like this:2*atan(x-3)+3

Or wait also tanh(x) is good. I think is perfect for your case

Try to plot it

tanh(x-3/5)+1

*Last edited by seerj (2005-12-29 03:21:16)*

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**krassi_holmz****Real Member**- Registered: 2005-12-02
- Posts: 1,905

Yes, yes.

And seerj's curves are close.

IPBLE: Increasing Performance By Lowering Expectations.

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