      # How to let the calculator know that a=0 in linear regression?

FX-991ES FX-991EX Linear Regression Statistics

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### #1 Ingvars_V

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Posted 26 November 2016 - 07:14 PM

Hello

I recently bought a Casio FX-991EX. I am in high school and orientate myself in physics. The statistics has a formula y=a+bx. I, for example, have an experiment where i get bunch of m (x) and l​ (y), i put those points in a graph and draw a line that suites all the points (linear regression) and calculate k from that line using ​kl=mg. I see that i could enter those values in the calculator and get b (y=a+bx where y is la is 0, x is m and b = g/k), but how can let the calculator know that a = 0 (or generally in every statistics formula that b or a is a number that i know) or something like that?

### #2 frankmar98

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Posted 26 November 2016 - 10:23 PM

Hello I study Chemistry and I have the same calc.

The calculator uses a formula for calculate separately a, and b, you can search it.

The thing what you want to do is called force interception in 0, for force the line pass through (0,0), this would make the linear regression more precise.

This is impossible to do with the fx-991 EX, I had used LibreOffice Calc on a Linux netbook to calculate it in the laboratory.

### #3 pan.gejt

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Posted 26 November 2016 - 11:30 PM

Well, you can calculate the coefficient manually. I found the relation in document "Reg_thru_origin.pdf". This document is interesting.

b=sum(xi*yi)/sum(xi^2),

both of these variables are calculated by the calc.

Edited by pan.gejt, 27 November 2016 - 10:45 AM.

### #4 Ingvars_V

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Posted 27 November 2016 - 12:47 PM 