# Thread: Equation for this graph

1. ## Equation for this graph

Can i get help with creating an equation for the two lines in on the graph above, the points are to the side of the graph

2. ## Re: Equation for this graph

tell you what

you write the data points as text as

$\{x_1, y_1\}, \{x_2, y_2\},$ etc.

and I'll fit a curve for you.

I'm not going to type all that in from the picture though.

3. ## Re: Equation for this graph

Ok thank you!!!!

Curve one: {32,0},{35 1.52},{45,7.62},{55,12.73},{90,21.08}

Curve two: {32,24.64},{35,26.16}.{45,32.26},{55,37.34},{90,45 .72}

4. ## Re: Equation for this graph

Ok thank you!!!!

Curve one: {32,0},{35 1.52},{45,7.62},{55,12.73},{90,21.08}

Curve two: {32,24.64},{35,26.16}.{45,32.26},{55,37.34},{90,45 .72}

Whoops didnt reply to ur comment

5. ## Re: Equation for this graph

Originally Posted by KeatonBuddy
Ok thank you!!!!

Curve one: {32,0},{35 1.52},{45,7.62},{55,12.73},{90,21.08}

Curve two: {32,24.64},{35,26.16}.{45,32.26},{55,37.34},{90,45 .72}

Whoops didnt reply to ur comment
curve 1 is $-0.00544151 x^2+1.03165 x-27.6779$

curve 2 is $-0.00541312 x^2+1.02809 x-2.94836$

6. ## Re: Equation for this graph

Are you not at all concerned with whether or not that answer is correct?

When I put x= 32 into $\displaystyle −0.00544151x^2+ 1.03165x−27.6779$, I get -0.2372, not 0.

7. ## Re: Equation for this graph

Originally Posted by HallsofIvy
Are you not at all concerned with whether or not that answer is correct?

When I put x= 32 into $\displaystyle −0.00544151x^2+ 1.03165x−27.6779$, I get -0.2372, not 0.
I checked a plot of the quadratic against the points. It's not perfect but it's pretty damn close.

Could it be improved by increasing the order of the model? Sure. Is it necessary? Almost certainly not.

8. ## Re: Equation for this graph

Originally Posted by romsek
I checked a plot of the quadratic against the points. It's not perfect but it's pretty damn close.

Could it be improved by increasing the order of the model? Sure. Is it necessary? Almost certainly not.
Um if you dont mind can i get how you found this equation

9. ## Re: Equation for this graph

Originally Posted by KeatonBuddy
Um if you dont mind can i get how you found this equation
mathematica's NonlinearModelFit[] function