#include<stdio.h>#include<math.h>int main(void){ double a,b,c,x1,x2; printf("请输入三个系数a,b,c\n"); scanf("%lf%lf%lf",&a,&b,&c); x1=(-b+sqrt(b*b-4*a*c))/(2.0*a); x2=(-b-sqrt(b*b-4*a*c))/(2.0*a); if(b*b-4*a*c<0) { printf("这个一元二次方程无解\n"); } else { printf("这个方程的根为%.2lf和%.2lf\n",x1,x2); } return 0;}