【c语言】求方程式 ax^2+bx+c=0 的根，分别考虑：1、有两个不等的实根 2、有两个相等的实根

// 求方程式 ax^2+bx+c=0 的根，分别考虑：1、有两个不等的实根 2、有两个相等的实根

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

int main()
{
int d;
int a,b,c;
double x,y;
double f;
printf("请输入a,b,c：");
scanf("%d%d%d",&a,&b,&c);
d = b*b-4*a*c;
f = sqrt(d);
if( d > 0)
{
x = ( ( -1 ) * b + f ) / ( 2 * a );
y =	( ( -1 ) * b - f ) / ( 2 * a );
printf("有两个实根：x = %f  y = %f\n",x,y);
}
else if( d == 0 )
{
x = ( ( -1 ) * b ) / ( 2 * a );
printf("此方程只有一个实根：x = y = %f\n",x);
}
else
printf("此方程没有实根\n");

return 0;
}

<img src="http://img.blog.csdn.net/20150423115503455?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhb3lhcWlhbjU1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />

<img src="http://img.blog.csdn.net/20150423115509602?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhb3lhcWlhbjU1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />

<img src="http://img.blog.csdn.net/20150423115630916?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhb3lhcWlhbjU1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />