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标题: [求助]gwd-28-30 [打印本页]

作者: exhilarating 时间: 2007-9-13 07:04 标题: [求助]gwd-28-30

Q30:

A rectangular photograph is surrounded by a border that is 1 inch wide on each side. The total area of the photograph and the border is M square inches. If the border had been 2 inches wide on each side, the total area would have been (M + 52) square inches. What is the perimeter of the photograph, in inches?

A. 34

B. 36

C. 38

D. 40

E. 42

I can only until

xy=M

(x+1)(y+1)=M+52

(x+1)(y+1)-xy=52

(x+2)y-xy=52

and solve x=25, y=26.

But can't find the perimeter=40, which is D.

Can anyone please help?

Thank you very much.

作者: exhilarating 时间: 2007-9-13 19:07

But according to , x=25, y=26, the answer is 2(25+26)=82

how come?

作者: IORIYAGAMI 时间: 2007-9-14 06:33

(x+1)*(y+1) = M; (x+2)*(y+2) = M + 52

作者: exhilarating 时间: 2007-9-15 19:22

这样算下来， x+y=49, 所以photograph的周长是98，那位xdjm给验算一下。感谢！！

作者: shawlen 时间: 2007-12-17 14:18

(X+2)(Y+2)=M,(X+4)(Y+4)=M+52,

2(X+Y)=40

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