2.程序：
main()
{
float absf(float x);
float f(float t);
float f1(float t);
float f2(float t);
float a[50],e;
int k=0;
a[0]=0.0,e=0.001;

for(k=0;k<49;k++)
  {
  a[k+1]=a[k]-f1(a[k])/f2(a[k]);
  if (absf(a[k+1]-a[k])<=e) break;
  }
if (k==48) printf("out  ");
      else printf("%d   ",k);
printf("%f  %f\n",a[k+1],f(a[k+1]));
}

float absf(float x)
{if (x<0) return -x;
     else return x;
}

float f(float t)
{return t*t*t*t+t*t*t+t*t+t+1;}

float f1(float t)
{return 4*t*t*t+3*t*t+2*t+1;}

float f2(float t)
{return 12*t*t+6*t+2;}