链接:http://noi.openjudge.cn/ch0111/02/
#include<bits/stdc++.h>
using namespace std;
double f(double x)
{
double x1[6];
x1[1]=x;
for(int i=2;i<=5;i++)
x1[i]=x1[i-1]*x;
return x1[5]- 15 * x1[4]+ 85 * x1[3]- 225 * x1[2]+ 274 * x1[1] - 121;
}
int main()
{
//freopen("t.txt","r",stdin);
double h=2.4,l=1.5;
while(h-l>1e-8)
{
double mid=(h+l)/2;
if(f(mid)>0)
{
l=mid;
}else
{
h=mid;
}
}
printf("%.6f",h);
return 0;
}