/*求一元二次方程的解*/
#include"stdio.h"
#include"math.h"
void main()
{
	int m;
	do
	{
		m=1;
		float a,b,c,delta,x1,x2,realpt,imagpt;
		printf ( "\n【求一元二次方程的解】\n" );
		printf ( "请输入一元二次方程的三个参数。\n" );
		scanf ( "%f%f%f",&a,&b,&c );
		if ( a!=0 )
		{
			delta=b*b-4*a*c; //求一元二次方程的△
			if ( delta>0 )
			{
				x1= ( -b+sqrt ( delta ) /2*a );
				x2= ( +b+sqrt ( delta ) /2*a );
				printf ( "方程的两个不等实根为：x1=%8.4f  x2=%8.4f\n",x1,x2 );
			}
			else if ( delta==0 )
			{
				x1=x2=-b/ ( 2*b );
				printf ( "方程的两个相等实根为：x1=x2=%8.4f\n",x1 );
			}
			else
			{
				delta=-delta;
				realpt=-b/ ( 2*a );
				imagpt=sqrt ( delta );
				printf ( "方程的两个共轭根为：\n" );
				printf ( "x1=%8.4f+%8.4fi\n",realpt,imagpt );
				printf ( "x2=%8.4f-%8.4fi\n",realpt,imagpt );
			}
		}
		else
			printf ( "不是一元二次方程！\n" );
	}
	while ( m==1 );

}