[計量] 兩題計量請教
看板GRE (GRE入學考試)作者LouisGarneau (Louis Garneau)時間8年前 (2016/08/05 20:25)推噓4(4推 0噓 7→)留言11則, 3人參與討論串6/9 (看更多)
1.If n is a positive integer and the product of all the integers from 1 to n,
inclusive, is a multiple of 990, what is the possible value of n ?
A.8
B.10
C.12
D.14
E.16
2.If a < b < 0, which of the following numbers must be positive?
Indicate all such numbers.
A.a-b
B.a^2-b^2
C.ab
D.a^2xb
E.a^2+ab^2
第一題不懂題目的意思，選了990的因數10
答案是CDE
第二題答案是BC
想問E選項除了直接代數字（有些代入是正有些是負，剛好代到都是正）
之外有沒有其他方法？
謝謝大家。
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