C Program to Find the Roots of a Quadratic Equation

# C Program to Find the Roots of a Quadratic Equation

In this example, we will learn to find the roots of a quadratic equation in C programming.

Remainder :

To understand this example, we should have the knowledge of the following C programming topics:

The standard form of a quadratic equation is:

`ax2 + bx + c = 0 `

Here, a, b and c are real numbers and a != 0

The term `b2-4ac` is known as the discriminant of a quadratic equation which tells the nature of the roots.

• If discriminant > 0, the roots are real and different.
• If discriminant = 0, the roots are real and equal.
• If discriminant < 0, the roots are complex and different.

## Program to Find Roots of a Quadratic Equation

``#include <stdio.h>#include <math.h>int main() {   int a, b, c, dis;  double root1, root2;  printf("Enter coefficients a, b and c: ");  scanf("%d %d %d", &a, &b, &c);  dis = b * b - 4 * a * c;  if (dis < 0) {    printf("First root = %.2lf + i%.2lf\n", -b/(double)(2*a), sqrt(-dis)/(2*a));    printf("Second root = %.2lf - i%.2lf\n", -b/(double)(2*a), sqrt(-dis)/(2*a));  }  else {    root1 = (-b + sqrt(dis)) / (2 * a);    root2 = (-b - sqrt(dis)) / (2 * a);    printf("root1 = %.2lf and root2 = %.2lf", root1, root2);  }  return 0;}``

Output

`Enter coefficients a, b and c: 2 3 4First root = -0.75 + i1.20Second root = -0.75 - i1.20`

In this program, we use `sqrt()` library function to find the square root of a number. To learn more, visit: sqrt() function.