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20140209, 05:01 #1
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Excel quadratic function calculator
Hello everyone. I have created a graphic calculator for quadratic function using some advices I saw here on the forum. By this, I want to share this document with the users of the forum.Função Quadratica.xlsm Good luck!

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Maudibe (20140220)

20140217, 07:03 #2
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Cool, i shall try it...when i eventually need such a thing

20140218, 09:38 #3
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Thanks. I might use this in class to show how changing the coefficients affects the shape of the parabola.
While I understand the purpose of the first series of controls (the green for the coefficients and the blue for the graphing window), what do the formulas in the orange boxes do?
Fred

20140219, 20:25 #4
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The orange boxes is used to show some information about the function, like concavity, function roots, delta value, but they are in portuguese (because it's my native language).

20140220, 09:56 #5
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thanks.
for my class, the roots and concavity are useful. We'll skip the delta value.

20140220, 17:22 #6
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xD...

20140220, 21:17 #7
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Very nicely done!

20140220, 23:08 #8
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This is very useful to me. But I wish there was an English version.

20140221, 10:33 #9
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I have difficult with just about any language other than English. However, I do teach algebra and we use most of the features of the spreadsheet  see my posting above about the green and blue controls. A subsequent posting from the author discussed the orange items. Not explicitly mentioned in that post was that the last orange box gives the yintercept of the parabola.

20140221, 13:00 #10
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To clean it up a little (you have the occasional spurious green points at 0,0], I would change your formula in Calculos!E8 to:
Code:=IF(delta<0,NA(),IF(coef_a=0,coef_c/coef_b,(coef_b+SQRT(delta))/(2*coef_a)))
Code:=IF(delta<0,NA(),IF(coef_a=0,coef_c/coef_b,(coef_bSQRT(delta))/(2*coef_a)))
Code:=IF(coef_a=0,"a= [" & round(Calculos!E8,2) & "; 0]",IF(delta<0,"Essa equação não possui raízes reais",IF(delta=0,"A raíz dessa equação é "& ROUND(Calculos!E8,2),"As raízes dessa equação são ["& ROUND(Calculos!E8,2)& "; 0] e ["& ROUND(Calculos!F8,2)& "; 0]")))

20140221, 13:28 #11
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Oh, thanks for that. I'll change this and repost. And I'll try to do an english version too. Cya...

20140221, 13:45 #12
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In case you were not aware, in English, what you term "Delta" is called the "discriminant" [the symbol for it is the uppercase Greek Delta (Δ)].
A style point, you probably should either refer to the intersection points for the parabola and the XAxis (for example, [5.3; 0] and [6.2; 0]) or the roots of the quadratic (for example, 5.3 and 6.2). The roots are not points they are just the Xvalues that solve the equation 0= Ax² + Bx + C. [though graphically they represent the intersection of the curve Y= Ax² + Bx + C and the XAxis]. You conflate the concepts in several calculations.
SteveLast edited by sdckapr; 20140221 at 13:47.

20140223, 13:15 #13
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Hey Steve, I'll be glad if you make a better version (or fix my version of that haha). If you can, make it and post for us
It'll be good for me to learn more about this topic and about excel...thx

20140224, 16:13 #14
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I can help anyone who wants to improve it. I have no need for it, so don't know what features would be desired to improve it. My comments were to correct what I considered errors and to help with some of the mathematical terms in English.
Steve

20140225, 00:16 #15
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For high school students, it would be useful to use the discriminant to tell the types of roots.
b^24ac = 0 : 1 real root
b^24ac < 0 : no real roots
b^24ac > 0 : 2 real roots
Might also indicate that if the coefficient of x^2 is positive, the parabola will open upward; otherwise opens downward.
Just two thoughts that came to my mind.