Results 1 to 15 of 21

20140209, 06:01 #1
 Join Date
 Feb 2014
 Location
 Rio das Pedras, Brazil
 Posts
 5
 Thanks
 0
 Thanked 1 Time in 1 Post
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!

The Following User Says Thank You to RrR2010 For This Useful Post:
Maudibe (20140220)

20140217, 08:03 #2
 Join Date
 Feb 2014
 Posts
 6
 Thanks
 0
 Thanked 0 Times in 0 Posts
Cool, i shall try it...when i eventually need such a thing

20140218, 10:38 #3
 Join Date
 Jan 2001
 Location
 West Long Branch, New Jersey, USA
 Posts
 1,873
 Thanks
 6
 Thanked 4 Times in 3 Posts
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, 21:25 #4
 Join Date
 Feb 2014
 Location
 Rio das Pedras, Brazil
 Posts
 5
 Thanks
 0
 Thanked 1 Time in 1 Post
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, 10:56 #5
 Join Date
 Jan 2001
 Location
 West Long Branch, New Jersey, USA
 Posts
 1,873
 Thanks
 6
 Thanked 4 Times in 3 Posts
thanks.
for my class, the roots and concavity are useful. We'll skip the delta value.

20140220, 18:22 #6
 Join Date
 Feb 2014
 Location
 Rio das Pedras, Brazil
 Posts
 5
 Thanks
 0
 Thanked 1 Time in 1 Post
xD...

20140220, 22:17 #7
 Join Date
 Aug 2010
 Location
 Pa, USA
 Posts
 2,187
 Thanks
 95
 Thanked 510 Times in 465 Posts
Very nicely done!

20140221, 00:08 #8
 Join Date
 Jul 2010
 Location
 York, SC
 Posts
 2
 Thanks
 0
 Thanked 0 Times in 0 Posts
This is very useful to me. But I wish there was an English version.

20140221, 11:33 #9
 Join Date
 Jan 2001
 Location
 West Long Branch, New Jersey, USA
 Posts
 1,873
 Thanks
 6
 Thanked 4 Times in 3 Posts
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, 14:00 #10
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
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, 14:28 #11
 Join Date
 Feb 2014
 Location
 Rio das Pedras, Brazil
 Posts
 5
 Thanks
 0
 Thanked 1 Time in 1 Post
Oh, thanks for that. I'll change this and repost. And I'll try to do an english version too. Cya...

20140221, 14:45 #12
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
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 14:47.

20140223, 14:15 #13
 Join Date
 Feb 2014
 Location
 Rio das Pedras, Brazil
 Posts
 5
 Thanks
 0
 Thanked 1 Time in 1 Post
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, 17:13 #14
 Join Date
 Jul 2002
 Location
 Pittsburgh, Pennsylvania, USA
 Posts
 11,225
 Thanks
 14
 Thanked 342 Times in 335 Posts
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, 01:16 #15
 Join Date
 Jan 2001
 Location
 La Jolla, CA
 Posts
 1,243
 Thanks
 19
 Thanked 46 Times in 45 Posts
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.