double a,b,c;
scanf(“%lf %lf %lf”,&a,&b,&c);
if((bb-4ac<0)||a==0)
printf(“Impossivel calcular”);
else {
printf(“R1 = %.5lf\n”,(-b+sqrt(bb-4ac))/(2a));
printf(“R2 = %.5lf”,(-b-sqrt(bb-4ac))/(2a));
}
//注意相关的(2a),符合优先级问题