public class RootFormula {    public static void main(String[] args){        double a=1.0;        double b=3.0;        double c=-4.0;        double r1=(-b+Math.sqrt(b*b-4*a*c))/2*a;        double r2=(-b-Math.sqrt(b*b-4*a*c))/2*a;        System.out.println(r1);        System.out.println(r2);        System.out.println(r1==1&&r2==-4?"测试通过":"测试失败");    }}