2013
12-30

# Can you solve this equation?

Now,given the equation 8*x^4 + 7*x^3 + 2*x^2 + 3*x + 6 == Y,can you find its solution between 0 and 100;

The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has a real number Y (fabs(Y) <= 1e10);

The first line of the input contains an integer T(1<=T<=100) which means the number of test cases. Then T lines follow, each line has a real number Y (fabs(Y) <= 1e10);

2
100
-4

1.6152
No solution!

#include<iostream>
#include<cstdio>
#include<cstring>

using namespace std;

const double eps=1e-10;

double y;

double f(double x){
return 8*x*x*x*x+7*x*x*x+2*x*x+3*x+6-y;
}

int main(){

//freopen("input.txt","r",stdin);

int t;
scanf("%d",&t);
while(t--){
scanf("%lf",&y);
double l=0,r=100,mid;
if(f(l)>eps || f(r)<eps){
puts("No solution!");
continue;
}
while(l+eps<=r){
mid=(l+r)/2;
if(f(mid)<eps)
l=mid+eps;
else
r=mid-eps;
}
printf("%.4lf\n",l);
}
return 0;
}