老師買了x包牛奶糖和(x-4)包水果糖，將所有的糖果平分給12位小朋友，已知牛奶糖每包有24顆，水果糖每包有30顆，每位小朋至少分得8顆糖果，但不超過15顆，則x之值為多少？
回答 (2)
2017-07-12 3:15 pm
✔ 最佳答案
Solx－4>0
x>4
24x+30(x－4)=54x－120
8<=(54x－120)/12<15
8<=(9x－20)/2<15
16<=9x－20<30
36<=9x<50
4<=x<4.5
x=5
2017-07-12 5:14 pm
8 <= [ 24x + 30(x-4) ] / 12 <=15
8 <= [ 4x + 5(x-4) ] / 2 <=15
16 <= 4x + 5(x-4) <=30
16 <= 4x + 5x - 20 <=30
36 <= 4x + 5x <=50
36 <= 9x <=50
9×4=36 or 9×5=45 , x = 4 or 5 ,
因 5(x-4) 須被 2 整除 (題目說 "將所有的糖果平分" )
若 x = 4 : 整除 ； x = 5 : 有餘，
所以 x = 4
8 <= [ 4x + 5(x-4) ] / 2 <=15
16 <= 4x + 5(x-4) <=30
16 <= 4x + 5x - 20 <=30
36 <= 4x + 5x <=50
36 <= 9x <=50
9×4=36 or 9×5=45 , x = 4 or 5 ,
因 5(x-4) 須被 2 整除 (題目說 "將所有的糖果平分" )
若 x = 4 : 整除 ； x = 5 : 有餘，
所以 x = 4
收錄日期: 2021-04-24 00:34:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170712070246AAqHUue