题解 | 计算一元二次方程

#include <stdio.h>
#include<math.h>

int main() {
    float  a,b,c;
    while(scanf(" %f %f %f",&a,&b,&c)!=EOF){
        if(a==0){
            printf("Not quadratic equation\n");
        }
        else if((b*b-4*a*c)>0){//判断有几个根
            float x1=0;
            float x2=0;//两个根
            float i=-b+sqrt(b*b-4*a*c);
            x1=i/(2*a);//求根
            float j=-b-sqrt(b*b-4*a*c);
            x2=j/(2*a);
            printf("x1=%.2f;x2=%.2f\n",x2,x1);
        }
        else if((b*b-4*a*c)==0){//判断有几个根
            float x1=0;
            float x2=0;//两个根
            float i=-b+sqrt(b*b-4*a*c);
            x1=i/(2*a);//求根
            if(x1==0){
                x1=0;
            }
            printf("x1=x2=%.2f\n",x1);
    }
    else if(b*b-4*a*c<0){
        float x1=0;
        float x2=0;
        float zhen=-b/(2*a);
        float xu=sqrt(4*a*c-b*b)/(2*a);
        printf("x1=%.2f-%.2fi;x2=%.2f+%.2fi\n",zhen,xu,zhen,xu);
    }
}
return 0;
}