How to write a program in C to find the root of a Quadratic Equation

#include<stdio.h>

int main()

{

int a=5,b=10,c=15,root,x,y;

   root=(b*b-4*a*c);

    x=(-b+root)/(2*a);

    y=(-b-root)/(2*a);

    printf("\n quadratic equation is %d and %d",x,y);

}

In case where user have to enter the value of the a,b,c variables then write the following code before the formula

And  the output will come according the value entered by user