作者Honor1984 (奈何上天造化弄人？)
看板Math
标题Re: [代数] 解未知数
时间Fri Apr 14 18:05:56 2023
※ 引述《xy210742 (Sam)》之铭言：
: 各位大大好，
: 题目：Two Identical rectangular prisms each have a height of 90 centimeters (c
: m). The base of each prism is a square, and the surface area of each prism is
: K cm^2. If the prisms are glued together along a square base, the resulting pr
: ism has a surface area of 92K/47 cm^2，what is the side length in cm of each
: square base?
: 希望各位大大可解惑一下
: 谢谢
正方形边长a(cm)
90a * 4 + 2a^2 = K
=> (184/47)a^2 + (360)(92/47)a = (92/47)K
假如题意是指两角柱的正方形底面相黏
90a * 4 *2 + 2a^2 = 92K/47
=> 2a^3 + 720a = (184/47)a^2 + 360(92/47)a
=> (90/47)a^2 - 360(2/47)a = 0
=> a^2 - 8a = 0
=> a = 8(cm)
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