1.If x is an integer greater than 1 and if y = x + 1/x,which of the following must be true?I.y x II.y is an integer.III.xy > x^2 (A) I only (B) III only (C) I and II only (D) I and III only (E) I,II,and III

1.If x is an integer greater than 1 and if y = x + 1/x,which of the following must be true?I.y x II.y is an integer.III.xy > x^2 (A) I only (B) III only (C) I and II only (D) I and III only (E) I,II,and III
1.If x is an integer greater than 1 and if y = x + 1/x,which of the following must be true?
I.y x II.y is an integer.III.xy > x^2
(A) I only
(B) III only
(C) I and II only
(D) I and III only
(E) I,II,and III

1.If x is an integer greater than 1 and if y = x + 1/x,which of the following must be true?I.y x II.y is an integer.III.xy > x^2 (A) I only (B) III only (C) I and II only (D) I and III only (E) I,II,and III
列表
x y
2 2+1/2
3 3+1/3
4 4+1/4
5 5+1/5
6 6+1/6
y =!x
套2 !2=2*1=2
套3 !3=3*2*1=6
因此 I项排除
y is an integer(整数),从上表可知y不可能是整数
xy > x^2
2*5/2 = 5 > 2*2=4
3*10/3 =10 > 3*3=9
因此III 是对的
答案是 (B) III only

选项I 到底是什么？（感叹号+x？）这道题看上去不难啊，这么半天没人解答应该就是因为不理解你这个选项的意思。我当时就是因为感叹号纠结的。。。如果真是感叹号，那就应该是阶乘了。即使你不懂阶乘，也可以判断，仅凭上面的条件，不能证明y可以确定地等于x的什么。这道题唯一能判断的就是（x+1/x)>x, 所以x*(x+1/x)>x^2. 因此只能选B.（iii是唯一正确的）我知道阶乘，但是答案不确定。虽然木...

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选项I 到底是什么？（感叹号+x？）这道题看上去不难啊，这么半天没人解答应该就是因为不理解你这个选项的意思。

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