include <stdio.h>
include <math.h>

int main()
{
     flaot solution(float a,flaot b,float c,float d);
     float a;
     float b;
     float c;
     float d;
     scanf("%f%f%f%f",&a,&b,&c,&d);
     printf("the soulution is %f\n",solution(a,b,c,d);

     return 0;
}
float
 
 solution(float a, float b, float c,float d)
{
    float x = 1.5;
    float x0;
    float f;
    float fd;

    while(fabs(x - x0)>= 1e-5)
    {
        x0 = x;
        f = a * x0 * x0 * x0  + b * x0 * x0 +c * x0 + d;
        fd = 3 * a * x0 * x0 + 2 * b * x0 +c;
        x = x0 - f / fd;  
    }

    return x;
}
 

轉自：https://blog.csdn.net/qq_31029351/article/details/53311285