Re: [問題] PP2-DS-80
※ 引述《spplen (起步向學走)》之銘言：
: 問題如下：
: If x and y are positive integers such that x = 8y + 12, what is the greatest
: common divisor of x and y ?
: (1) x = 12u, where u is an integer.
: (2) y = 12z, where z is an integer.
: ans.B
: 麻煩解答了!謝謝!
(1)
x=12u ==> 12 u = 8y + 12 ==> y = [ 12 (u-1) ] / 8 ==> 不充分
(2)
y=12z ==> x = 8 (12z) + 12 ==> x = 12 ( 8z + 1 ) ==> 充分
可知 where z is an integer , x y the greatest common divisor 為12
如果有錯 請見諒^^"
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※ 編輯: onznka 來自: 61.228.212.114 (03/08 22:48)
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