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歡迎您訪問數學考題練習:把棱長為4的正方體分割成29個棱長為整數的正方!

數學考題練習:把棱長為4的正方體分割成29個棱長為整數的正方

更新時間:2024-01-12 14:01:47作者:貝語網校

把棱長為4的正方體分割成29個棱長為整數的正方體(且沒有剩余),其中棱長為1的正方體的個數為________.

試題答案

24

試題解析

從三種情況進行分析:(1)只有棱長為1的正方體;(2)分成棱長為3的正方體和棱長為1的正方體或棱長為3的正方體和棱長為2的正方體和棱長為1的正方體;(3)分成棱長為2的正方體和棱長為1的正方體.

解答:棱長為4的正方體的體積為64,

如果只有棱長為1的正方體就是64個不符合題意排除;

如果有一個3×3×3的立方體(體積27),有1×1×1的立方體37個,37+1>29,不符合題意排除;

如果有一個3×3×3的立方體(體積27),有一個2×2×2的立方體(體積8),就只能有1×1×1的立方體29個,1+1+29>29,不符合題意排除;

所以應該是有2×2×2和1×1×1兩種立方體.

則設棱長為1的有x個,則棱長為2的有(29-x)個,

解方程:x+8×(29-x)=64,

解得:x=24.

所以分割的立方體應為:棱長為1的24個,棱長為2的5個.

故答案為:24.

點評:本題考查了一元一次方程組的應用,立體圖形的求解,解題的關鍵是分三種情況考慮,得到符合題意的可能,再列方程求解.

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