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