#include<stdio.h>
float Q_gen(float c);
void main()
{
        float X1,y;
        X1=3;

         y=Q_gen(X1);
       if(y<0)
       {
          X1=(X1+0.1);
          y=Q_gen(X1);
       }
        printf("方程的根为%f",X1);
}
float Q_gen()
{
    float c;
    float y;
    y=c*(c*(c-c*5)+16)-80;
    return(y);
}