PTA-- 实验3-1 求一元二次方程的根

#include
#include
int main()
{
	//定义变量 
	double a, b, c, x1, x2, x3, A;
	
	//输入数字
	scanf("%lf %lf %lf",&a, &b, &c);
	
	//算式计算
	
	A = b*b - 4*a*c;
	x1 = ( -b + pow( A, 1.0/2.0) )/ (2*a);
	x2 = ( -b - pow(A, 1.0/2.0) )/ (2*a);
	x3 = pow(4*a*c - b*b,1.0/2.0)/(2*a);
	

	if(A >= 0)
	{
		if(A == 0 && a != 0 && b != 0)
	        printf("%.2lf",x1);
	        
	     if(A > 0 && a != 0 && b!=0)
	        printf("%.2lfn%.2lf",x1,x2);
	       
		   
		    
	     if(a == 0 && b == 0 && c == 0)
	        printf("Zero Equation");
	        
	     if(a == 0 && b == 0 && c != 0)    
	    printf("Not An Equation");
	        
	     if(a == 0 && b != 0 && c != 0) 
		    printf("%.2lf",-c/b);   
	}
	
	else
	{ 
	    printf("%.2lf+%.2lfin",-b / 2*a,x3);
	    printf("%.2lf-%.2lfin",-b / 2*a,x3);
	}
	return 0;
}