#include <bits/stdc++.h>
using namespace std;
double f(double x){return 2*x*x*x+3*x-1;}
int main(){
double a=0,b=1,mid,tol=1e-8;
while(fabs(b-a)>tol){
mid=(a+b)/2;
if(f(a)*f(mid)<0)b=mid;
else a=mid;
}
cout<<setprecision(10)<<fixed<<mid;
}
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