Probably simple error - i am a newbie to the world of programming

Why does it display a zero at the end?

Code:

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

/* Function Prototypes */

/*double	ffunction(),
		dfunction(),
		calcfunction(),
		incguess(),
		displayfound(),
		displaynotfound();*/

double ffunction(double beta, double gamma, double delta, double x, double fx);


int
main(void)
{
	double	b,
		c,
		d,
		guess,
			
		ans=0;


	printf("please enter b, c, d and guess>\n");
	scanf("%lf %lf %lf %lf", &b, &c, &d, &guess);
	ffunction(b,c,d,guess,ans);
	printf("fx= %f\n", ans);
	return(0);

}
double
ffunction(double beta, double gamma, double delta, double x, double fx){
	fx = (pow(x,3))+beta*pow(x,2)+gamma*x+delta;
	return (fx);
}

As far as I can tell you do nothing with the return value of ffunction(). fx inside ffunction is a local variable, it will not affect ans.

Read through Lesson 4: Functions. That should clear up most of your confusion. Additionally, you should set your compiler warnings to max and pay attention to them; that would have pointed out the problem for you.