请教两道prep上的题目

kleinesonne

请教两道题目 都是prep上的

1. prep-DS2-188
Is x^4 + y^4 > z^4 ?
(1) x^2 + y^2 > z^2
(2) x + y > z
答案是E
但是我觉得是A
如果把(1)两边同平方，因为2(X^2)(y^2)一定大于0，所以就可以得到x^4 + y^4 > z^4了呀。。。。

2.prep-ps2-76
A hiker walking at a constant rate of 4 miles per hour is passed by a cyclist traveling in the same direction along the same path at a constant rate of 20 miles per hour.  The cyclist stops to wait for the hiker 5 minutes after passing her, while the hiker continues to walk at her constant rate.  How many minutes must the cyclist wait until the hiker catches up?
(A)  
(B) 15
(C) 20
(D) 25
(E)  
答案是C
这道题目我完完全全没有看懂。。。。

请大家帮忙看看吧~~~
谢拉

kleinesonne

先谢谢啦~~~~~~~~
第一道题目真的是哦 我的脑子怎么就突然转不过来了。。。。。
第二道题目已经演变成了一个语法题了。。。。我看着你的翻译 发现我还是中英文对照不上。。。
能帮我解释一下这句话到底怎么拆分看么？
“The cyclist stops to wait for the hiker 5 minutes after passing her, while the hiker continues to walk at her constant rate.  How many minutes must the cyclist wait until the hiker catches up？”

谢谢哦

kleinesonne

嗯嗯
我顿悟了~~~~

谢谢啦~~~~~~~~~~~~