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第一道. If n and y are positive integers and 450y=n^3, which of the following must be an integer? 1. y/[3*(2^2)*5] 2. y/[(3^2)*2*5] 3. y/[3*2*(5^2)] 选项: A. None B.1only C.2only D.3only E.1,2and3
答案是B (已解决^^)
第二道:2^x - 2^(x-2)=3(2^13), 求x A.9 B.11 C.13 D.15 E.17
答案是D 已解决 第三道:If x is an integer, is (x^2+1)(x+5)an even number? (1)x is an odd number (2)Each prime factor of x^2 is greater than 7
答案是D。我不明白条件2的怎么推导出答案
第四道:The cost of delivering for an order of desk chairs was $10.00 for the first chair, and $1.00 for each additional chair in the order. If an office manager placed an order for n desk chairs, is n>24? (1) The delivery cost for the order totaled more than $30.00 (2) The average(arithmetic mean) delivery cost per chair of the n chairs was $1.36
答案是B。同样不明白条件2如何能推导出答案…… 已解决 求帮忙~谢谢大家! |
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