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How to make a Dynamic Calculator to solve a quadratic equation?


Taking my first steps in the world of Mathematica Programming.


The aim of my program was to modify Wolfram's dynamic calculator
(which performs an addition subtraction and a product - in response to the user inputting two values used to perform these operations)
to now take three input and display on the three outputs:



[1] the quadratic equation to be solved
[2] the roots of this quadratic equation
[3] the discriminant of this equation


The three things (in red text) which you have to input are:


first input box is coefficient a
second input box is coefficient b
third input box is coefficient c


These coefficients represent a,b and c in the quadratic equation ax2+bx+c


So the Wolfram Demonstration & My attempt (the code below) look like this: http://www.controlmanchester.com/2013/08/01/quadratic-equation-images/


The code for the original program is available here: http://reference.wolfram.com/mathematica/example/ConstructADynamicCalculator.html



This is the code that I have written (modified really):


 DynamicModule[ 
      {a = 0, b = 0, c = 0}, 
      Deploy[ 
       Style[ 
        Panel[ 
         Grid[ 
          Transpose[
        {
        {

        Style["input a ", Red],
        Style["input b", Red],
        Style["input c", Red],
    "here is the equation",
    "here is the value of the discriminant",
    "here are the roots"},

     {InputField[Dynamic[a], Number],
     InputField[Dynamic[b], Number],
     InputField[Dynamic[c], Number],

     InputField[Dynamic[a*x^2 + b*x + c],Enabled -> False],
     InputField[Dynamic[b]^2 - (4*Dynamic[a]*Dynamic[c]) , Enabled -> False],
     InputField[Dynamic[a b], Enabled -> False]}
            }
                ]
    , Alignment -> Right]
    , ImageMargins -> 10]
       , 
    DefaultOptions -> {InputField -> {ContinuousAction -> True, 
    FieldSize -> {{5, 30}, {1, Infinity}}}}]

    ]
    ]

I have discovered, via trial and error, that within an input field I cannot simply try something like
Solve[x^2 + a x + 1 == 0, x] or Roots[ ].


I think this is where the heart of my problem lies.


At the moment the variables I put in do propagate down and show the coefficients of the quadratic, but I cannot get any further with it.


Any help, or guidance to things I should read are most welcome.


Many Thanks, David


p.s. I have seen from the answer by Mike Honeychurch that I have not described the problem as clearly as possible. I have edited the post :) I hope this makes my problem easier to understand




Answer



My first thought was this:


Manipulate[
 Grid[
  {
   {TraditionalForm[u]},
   {"Equation", Row[{u, " = 0"}]},
   {"Solutions", Solve[u == 0, x]},
   {"Roots", Roots[u == 0, x]},
   {"Discriminant", Discriminant[u, x]}

   }, Alignment -> Left], 
 {{u, x^2 + 2 x + 1}},
 BaseStyle -> FontSize -> 16]

equationsolver


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