问题
填空题
面积为S的一切矩形中，其周长最小的矩形的边长是______．
答案
设矩形的长为x，宽为y则
S=xy
周长l=2（x+y）≥4
=4xy S
当且仅当x=y=
时，l最小为4s s
故答案为S
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面积为S的一切矩形中，其周长最小的矩形的边长是______．
设矩形的长为x，宽为y则
S=xy
周长l=2（x+y）≥4
=4xy S
当且仅当x=y=
时，l最小为4s s
故答案为S
| 用方框中所给单词的适当形式填空，使短文正确、通顺。每词限用一次。 | |
start a special day 1 Buy Nothing Day. They don't want anyone to go 2 on that day. Buy Nothing Day is on November 29. It is 3 Thanksgiving. Often, before Christmas we see many ads. in 4 and on TV 5 us to "buy, buy, buy!" The idea for Buy Nothing Day 6 in Vancouver, Canada. Now people all over the world 7 Buy Nothing Day. In California, the U.S., 8 and children get 9 to read stories, sing songs and draw pictures. The children talk about 10 they can't get many toys. |