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

float f(float);     //  Function
float ff(float);    //1st Derivative
float nut(void);

int main() {
    float z;
    z=nut();
    printf("Koren' yravneniya: x=%.10f\n\n",z);
}

float f(float x) {
    return x*x*cos(3.0*x)+0.5;
}

float ff(float x) {
    return 2*x*cos(3.0*x)-3*x*x*sin(3.0*x);
}

float nut() {
    float x,xx,e;
    printf("Vvedite x0, eps:\n");
    scanf("%f%f",&x,&e);
    while(true) {
        xx=x-f(x)/ff(x);
        //printf("x=%.10f\n",xx);
        if(fabs(f(xx))<e) break;
        x=xx;
    }
    return xx;
}