Program for Polynomial Solution without Formula, Numerical Analysis

Given a polynomial equation, write a program to check whether one of its roots lies within a given range. No formula, such as the quadratic formula for binomials is to be used.

Last Reviewed and Updated on June 24, 2017
Posted by Parveen(Hoven),
Aptitude Trainer and Software Developer

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C/C++ Program for Polynomial Solution without Formula, Numerical Analysis

Determine whether the following quadratic equation has a root between -1.0 and +1.0. If it exists, print that root to an accuracy of two decimal places. Do not use the quadratic formula. The equation is: 4x2 + 10x - 9 = 0

#include <iostream>
 
using namespace std;
 
int main()
{
 int counter = 0;
    
 // start from x = -1.0f
 float x = -1.0f;
 
 while(true)
 {
     // increment by 0.001
     // small steps -1.0, -.999, -.998, and so on
     x += 0.001f;
 
     // check after 100 increments
     if(counter++ == 100)
     {
         // if x has become larger than
         // 1 quit
         if(x > 1.0f)
         {
             cout << "No solution in -1 and +1";
 
             return 0;
         }
 
         // set increment counter to zero
         counter = 0;
 
     }
 
     cout << "x = " << x << endl;
 
     // caculate the equation expression
     float equation = (4 * x * x) + (10 * x) - 9;
 
     // make absolute, positive
     if(equation < 0)
     {
         equation *= -1;
     }
 
     // if it is almost zero
     // we have the solution
     if(equation < 0.01)
     {
         cout << "root = " << x << endl;
 
         break;
     }
        
 }
 
    return 0;
}

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This Blog Post/Article "Program for Polynomial Solution without Formula, Numerical Analysis" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-06-24.


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