Newton Raphson Method

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

float f(float);
float f1(float);

int main(){
	float x, x1,x2,y,t,m;
	printf("Enter the intial value:\n");
	scanf("%f",&x);
	x1=f(x);
	x2=f1(x);
	if(x2==0){
		printf("\nError!");
		main();
	}
	do{
		t=x;
		y=x-(f(x)/f1(x));
		m=t-y;
		x=y;
	}while(fabs(m)>0.0009);
	printf("\n\nThe root is: %.4f",y);
	getch();
}

float f(float x){
	return((x*x)-(4*x)-10);
}

float f1(float x){
	return((2*x)-4);
}