double a = 1.0;double b = 3.0;double c = -4.0;// 求平方根可用 Math.sqrt():// System.out.println(Math.sqrt(2)); ==> 1.414// TODO:double r1 = 0;double r2 = 0;double x = Math.sqrt(b*b-4*a*c);r1 = (-b+x)/(2*a);r2 = (-b-x)/(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");