# Cant find the equation of thi line

1. May 6, 2007

### nivisk

urgent..cant find the equation of thi line

this is a home work assig for tomorrow

i have a set of points on a graph....which makes a curve...the points are in huge numbers...it represents the focal length etc plz help me...i need to find an equation for that curve.....

here is the file with graph
http://files.filefront.com/New_Microsoft_Office_Excetxls/;7447761;/fileinfo.html

Last edited: May 6, 2007
2. May 6, 2007

### HallsofIvy

What??? Pretty much nothing you have said here makes sense! How can we help you do anything if we have no idea what curve or what points you are talking about? How does a curve "represent" a number?

3. May 6, 2007

### nivisk

sir i will tell you in detail

i have a set of points.....

which i plot on a graph....and i get a line which is lil bit curved

the problem is i need to find an equation for this line...

and i dont know which theory or what to do..
plz do help

4. May 6, 2007

### Office_Shredder

Staff Emeritus
Do you know what kind of graph it's supposed to be? Can you tell us what the points are? Do you know the context in which these points were determined?

Basically, you've given us no information here

5. May 6, 2007

### nivisk

i will give you in full detail...i will upload the graph now

6. May 6, 2007

7. May 6, 2007

### Feldoh

Could you just list the coords of the points?

8. May 6, 2007

### Office_Shredder

Staff Emeritus
From first glance it appears to be some sort of x-r for r some positive number.... you can actually get excel to give you a trendline, but the equation isn't nearly as good as one could want. It's actually probably more like 1/(x+k) for some k a constant

9. May 6, 2007

### Werg22

Seems quite linear to me, y = -0.000026704286*x+1.5329355 gives deviations of (in absolute value)

0.001906192
0.000880503
0.000652092
0.000377772
0.000542125
0.001377028
0.001465157
0.001604714
0.000448685
0.001621043

This gives an average deviation of 0.001087531, quite a small value.

10. May 6, 2007

### Werg22

If you want to get really accurate, the rational function

(6878435.6+633131.5*x)/(1+425906.02*x+(-1.3161499)*x^2)

gives really good results, with an average deviation of 0.00031

Edit; I used Graph, a free and useful program, you can download it at