求一元二次方程的解

#include <stdio.h>#include <math.h>int main(){    float a,b,c,x1,x2,dt;    printf("inpute a b c:");    if(scanf("%f%f%f",&a,&b,&c)<3)    {        printf("please inpute number!\n");        return 0;    }    dt=b*b-4*a*c;    if(dt>=0)    {        x1=(-b+sqrt(dt))/(2*a);        x2=(-b-sqrt(dt))/(2*a);        printf("x1=%f,x2=%f\n",x1,x2);    else    {        printf("input invalid\n");        return 0;    }return 0;}