double function(double x)
{
	double result;
	//result = log(x + 2) - 2 * pow(x, 2) + 1; //ln(x+2)-2*x^2+1
	//result = pow(x, 3) - 2 * x + 2;	//x^3 - 2*x + 2
	//result = -5*pow(x,3)+8*pow(x,2)+3*x-1 ;//-5*x^3+8*x^2+3*x-1
	result = tan(x);
	return result;
}
double derivative_of_function(double x)
{
	double result;
	result = 1 / (cos(x)*cos(x));
	return result;
}