## 1.07.2012

Q. Write a program to find the roots of a quadratic equation.

Ans.

Process of finding root of quadratic equation in C program:
The roots of any quadratic equation of the the form,

ax2+bx+c=0
has minimum two roots.
The formula of calculating these roots are as:

Where:r1,r2 are roots. First of all user entered values of a,b and c. Then it finds out numerator- which is the discriminate. Then checks if the numerator is greater, equals or less than zero. Prints out the results according to the situation.

/*program to find the root of a quadratic equation*/
#include<stdio.h>

#include<conio.h>
#include<math.h>
int main()
{
int a,b,c;
float r1,r2,up;
printf("Enter value of a : ");
scanf("%d", &a);
printf("Enter value of b : ");
scanf("%d", &b);
printf("Enter value of c : ");
scanf("%d", &c);
up=(b*b)-(4*a*c);
if(up>0)

{
printf("\n ROOTS ARE REAL ROOTS\n");
r1 = ((-b) + sqrt(up)) /(2*a);
r2 = ((-b) - sqrt(up)) /(2*a);
printf("\n ROOTS : %f, %f\n", r1, r2);
}
else if(up==0)
{
printf("\n ROOTS ARE EQUAL\n");
r1 = (-b/(2*a));
printf("\n ROOT IS...: %f\n", r1);
}
else
printf("\n ROOTS ARE IMAGINARY ROOTS\n");
getch();

return 0;
}

Output:-

Enter value of a : 6
Enter value of b : -13
Enter value of c : 6
ROOTS ARE REAL ROOTS
ROOTS : 1.500000, 0.666667

Enter value of a : 1
Enter value of b : 1
Enter value of c : -2
ROOTS ARE REAL ROOTS
ROOTS : 1.000000, -2.000000