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标题: 请教一道模考题 [打印本页]

作者: margland    时间: 2003-7-8 20:37     标题: 请教一道模考题

A tailor trims 4feet from opposite edges of a square piece of cloth and 5 feet from the other two edges. If 120 square feet of cloth remain , what was the length of a side of the original piece of cloth?
a 12 b 20 c 24 d 26 e40
答案是b20 我不太理解这个是怎么割的,这块布,看了答案还说不懂
作者: tongxun    时间: 2003-7-9 22:42

(x-4)(x-5)=120
x^2 -9x +20=120
x^2 -9x +140=0
我所能理解的就是这样了,但割不出20来(可能我想错了)
我的理解:
长缩短了4F,宽缩短了5F,则剩下的东西就从一个正方形变成一个长方形。

真的不好意思,没真正解答出来。
作者: margland    时间: 2003-7-10 00:12

it seems that (x-8) (x-10)=120  than the answer is 20
作者: northying    时间: 2003-7-10 21:55

为什么减8?
布的方形布的对边-4F,另2个对边-5F。或许是长方形裁成正方形。
这是我猜的,解释的英文是什么?
作者: tongxun    时间: 2003-7-10 23:40

I do not agree with you margland,because there is no such word as respectively in the question to illustrate cutting 5 feet in two sides。Would you mind copying the answer here, giving us an opportunity to discuss this question and thus figure it out?
作者: northying    时间: 2003-7-11 10:55

还是正方形裁成长方形。。。

我也希望看原版英文的解释。
作者: fengqiwu    时间: 2003-7-12 09:08

from opposite edge(s) 和 from the other two edge(s)应该是指四个边吧,如果这样,则应为(x-8) (x-10)=120 ,正方型裁成长方形
作者: northying    时间: 2003-7-12 21:14

clever

Thanks




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