1) If there are more than 2 members in a certain list, is each of the number in the list equal to zero? (1) The product of any two number in the list is equal to 0 (2) The sum of any two number is equal to 0 答案是B 条件一可以举反例,1,0,0 但是条件二不太明白,怎么证明呢?
2 Is x between 0 and 1? (1) X is between -1/2 and 3/2 (2) ¾ is ¼ more than X 答案是B 不太明白。条件二不是说 3/4-1/4>X,那也就是x<1/2为什么可以由条件二单独算出x between 0 and 1?
另外还有一道完全没看懂的题目,能不能麻烦牛牛们给翻译一下啊? Alice’s take-home pay last year was the same each month, and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of that portion of her monthly take-home pay that she did not save. If all the money that she saved last year was from her take-home money. What fraction of her take-home pay did she save each year? 这道题目答案是1/5完全不明白 黄色高亮这句话的意思,所以不知道怎么做啊?