# C Program Program to Calculate the Roots of a Quadratic Equation

by Dinesh Thakur Category: C Programming (Pratical)

The roots of a quadratic equation are real if discriminator b2-4ac is greater than or equal to zero; otherwise they are complex conjugate. However, if the roots are complex conjugate, i.e., if b2-4ac<0, the evaluation of expression sqrt (b*b-4*a*c) causes a domain error and the program halts abruptly.

```#include <stdio.h>#include <conio.h>#include <math.h>void main(){    double a,b,c,d,root1,root2;    clrscr();    printf("Enter Value for a : ");    scanf("%lf", &a);    printf("Enter Value for b : ");    scanf("%lf", &b);    printf("Enter Value for c : ");    scanf("%lf", &c);    if (a==0.0)        {              printf ("\n a Should NOT be 0");              exit(0);        }             d = b * b - 4 * a * c;             if ( d > 0.0 )              {                   d = sqrt( d );                   root1 = ( -b + d ) / ( 2 * a );                   root2 = ( -b - d ) / ( 2 * a );                   printf("\nThe Roots %.4lf and %.4lf were Found\n\n", root1, root2 );              }                   else if ( d == 0.0 )             {                   root1 = -b / ( 2 * a );                   printf("\nA Single Root, %.4lf, was Found\n\n", root1 );             }           else            {                  printf("\nNo real roots were found\n\n");            }                  getch();}
```

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