求一元二次方程的两个实数根
#include <stdio.h>
#include <math.h>//包含 sqrt()函数,求平方根
int main()
{
double a,b,c,disc,x1,x2,p,q;//定义为double类型,满足计算精度要求
printf("Please enter a,b,c in order:\n");//提示用户输入
scanf("%lf%lf%lf",&a,&b,&c);//注意用 %lf
disc=b*b-4*a*c;
if(disc<0)//判断是否有根
printf("This question hasn't real roots\n");
else
{
p=-b/(2.0*a);
q=sqrt(disc)/(2.0*a);
x1=p+q;
x2=p-q;
printf("real root:\nx1=%7.2f\nx2=%7.2f\n",x1,x2);
}
return 0;
}