...4ac大于0、等于0和小于0时的根,并输出结果。答:include<stdio.h> include<math.h> main(){ void x(float,float,float,float);void y(float,float,float);float a,b,c,d=0;printf("输入a b c的值:\n");scanf("%f %f %f",&a,&b,&c);d=(b*b)-(4.0*a*c);if (d>0)x(a,b,c,d);else if (d==0)y(a,b,c);else...