王朝 第十一周 牛顿

#include <stdio.h>
#include <math.h>
  double solut(double ,double ,double ,double );
int main()
 {

  double solut(double ,double ,double ,double );

  double a,b,c,d;

  scanf("%lf%lf%lf%lf",&a,&b,&c,&d);

  printf("%.2f",solut(a,b,c,d));;

  return 0;

 }
   double solut(double a,double b,double c,double d)
   {
       double x=1,x0;
       do
       {
           x0=x;
           x=x0-(a*x*x*x+b*x*x+c*x+d)/(3*a*x*x+2*b*x+c);
   }while(fabs(x-x0)>=1e-5);
return x;
}