Quadratic Equation program in C

In this article, you will learn to find the roots of a quadratic equation in C Language.

The standard form of a quadratic equation is:

ax2 + bx + c = 0, 
where a, b and c are real numbers

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

  • If the discriminant is greater than 0, the roots are real and different.
  • If the discriminant is equal to 0, the roots are real and equal.
  • If the discriminant is less than 0, the roots are complex and different.

Addition of two number program in C.

#include <stdio.h>

#include <math.h>

int main()


	double a, b, c, discriminant, root1, root2, realPart, imgPart;	

	printf("Enter coefficient a: ");



	printf("Enter coefficient b: ");


	printf("Enter coefficient c: ");



	discriminant = b * b - 4*a*c;


	//Condition for real and equal roots

	if(discriminant == 0)


			root1 = root2 = -b / (2 * a);

			printf("\nFor the coefficients a = %.2lf, b = %.2lf and c = %.2lf \n\nroot1 = root2 = %.2lf", a, b, c, root1 );





			//Condition for real and different roots

			else if(discriminant > 0) 


					//sqrt function returns square root


					root1 = (-b + sqrt(discriminant)) / (2 * a);

					root2 = (-b - sqrt(discriminant)) / (2 * a);


					printf("\nFor the coefficients a = %.2lf, b = %.2lf and c = %.2lf \n\nroot1 = %.2lf and root2 = %.2lf", a, b, c, root1, root2);



					//Condition for if roots are not real



						realPart = -b / (2 * a);

						imgPart = sqrt(-discriminant) / (2 * a);



						printf("\nFor the coefficients a = %.2lf, b = %.2lf and c = %.2lf \n\nroot1 = %.2lf + %.2lfi and root2 = %.2lf - %.2lfi", a, b, c, realPart, imgPart, realPart, imgPart);



						return 0;





Enter coefficient a: 1

Enter coefficient b: 4

Enter coefficient c: 4

For the coefficients a = 1, b = 2 and c = 3

root1 = root2 = -2.00

In this program, the sqrt() library function is used to find the square root of a number.

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