C program to find roots of a quadratic equation

Suppose assume a equation ax^2+bx+c=0

if b^2-4ac=0 then the roots are real and equal

if b^2-4ac<0 then the roots are imaginary and unequal

if b^2-4ac>0 then the roots are real and unequal

#include <stdio.h>
#include <math.h>
int main(){
    float a,b,c,d,root1,root2,realpart,imagpart;
    printf("Enter coefficients a,b and c: ");
    scanf("%f %f %f",&a,&b,&c);
    d=b*b-4*a*c;
    if(d>0){
        root1=(-b+sqrt(d))/(2*a);
        root2=(-b-sqrt(d))/(2*a);
        printf("root1=%.2f and root2=%.2f",root1,root2);
    }
    else if(d==0){
        root1=root2=-b/(2*a);
        printf("root1=root2=%.2f",root1);
    }
    else{
        realpart=-b/(2*a);
        imagpart=sqrt(-d)/(2*a);
        printf("root1=%.2f+%.2fi and root2=%.2f-%.2fi",realpart,imagpart,realpart,imagpart);
    }
}

Output:

Enter coefficients a,b and c: 3
9
12
root1=-1.50+1.32i and root2=-1.50-1.32i