【数学讨论稿】十月溯雪讨论稿201-300 (Nov 7, 23:00)

patricklv

206, b=1330

patricklv

211 From the question, we should know x has to be 1>x>-1. 1. 1>x^2,  1>x>-1 Sufficient. 2. Sufficient
212. x-y< x^2-y^2?
       x-y<(x+y)(x-y)
       1<x+y have to be satisfied. B itself is sufficient

Joyceeei

patricklv 发表于 2015-11-3 06:10
211 From the question, we should know x has to be 1>x>-1. 1. 1>x^2,  1>x>-1 Sufficient. 2. Sufficien ...

212 the premise of dividing both sides by x-y should be x-y>0

wonglam127

感谢分享！               

沁怡菇凉

辛苦哦dear～

awillleadaway

辛苦了，几位数学君！！

Evelynmiky-tea

棒！！！！！！！！！！！！！！！！！！！！

patricklv

Joyceeei 发表于 2015-11-3 07:54
212 the premise of dividing both sides by x-y should be x-y>0

true, agree

sj8cloud

patricklv 发表于 2015-11-3 06:10
211 From the question, we should know x has to be 1>x>-1. 1. 1>x^2,  1>x>-1 Sufficient. 2. Sufficien ...

个人建议从两个条件往回推，而且并不一定是得出是的结果，否也是可以，只要能判断其真假

sj8cloud

沁怡菇凉 发表于 2015-11-3 08:27
辛苦哦dear～

我这才刚开始，感谢元老慰问！