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標題:
朋友給我的問題!!!!!!!!!!!
發問:
1.一位魔術師每次可把 2 塊餅和 1 條芝士腸變成 2 條芝士腸和 2 隻香蕉，或把1 塊餅和 2 條芝士腸變成 3 隻香蕉。若他現有 5 塊餅和 2 芝士腸，問最多可得到多少隻香蕉呢？ 2.甲今年的年齢是乙的 7 倍；過若干年，甲的年齡是乙的 6 倍；再過若干年，甲的年齡分別是乙的 5 倍、4 倍、3倍、2倍。問甲今年幾歲？ 請給予答案及解釋~~~~~~~~~~ 朋友的朋友的朋友
最佳解答:
(1) Let X = 餅, Y = 芝士腸, Z = 香蕉 Let A: 2X 1Y ---> 2Y 2Z Let B: 1X 2Y ---> 3Z We have: 5X 2Y ----(B)----> 3X 3Y 3Z ----(A)----> 1X 4Y 6Z ----(B)----> 2Y 9Z Therefore, 9 隻香蕉 *********************************** (2) Let x = 甲今年的年齢, y = 乙今年的年齢 x = 7y ................................................(1) x+a = 6(y+a) ......................................(2) x+b = 5(y+b) ......................................(3) x+c = 4(y+c) ......................................(4) x+d = 3(y+d) ......................................(5) x+e = 2(y+e) ......................................(6) where 0 < a < b < c < d < e. Put (1) into (2), 7y+a = 6y+6a y = 5a x = 35a You may go on solving the equation if you like, but I would use the method of inspection here. x = 35 or 70 (135+ not likely for ages) This year: x=35, y=5 2st year: x=36, y=6 5th year: x=40, y=10 10th year: x=45, y=15 25th year: x=60, y=30 Therefore 甲今年的年齢 = 35 2007-05-26 01:16:44 補充： Sorry, for (1) should be:5X 2Y ----(A)----> 3X 3Y 2Z ----(A)----> 1X 4Y 4Z ----(B)----> 2Y 7Z7隻香蕉
其他解答:
朋友給我的問題!!!!!!!!!!!
發問:
1.一位魔術師每次可把 2 塊餅和 1 條芝士腸變成 2 條芝士腸和 2 隻香蕉，或把1 塊餅和 2 條芝士腸變成 3 隻香蕉。若他現有 5 塊餅和 2 芝士腸，問最多可得到多少隻香蕉呢？ 2.甲今年的年齢是乙的 7 倍；過若干年，甲的年齡是乙的 6 倍；再過若干年，甲的年齡分別是乙的 5 倍、4 倍、3倍、2倍。問甲今年幾歲？ 請給予答案及解釋~~~~~~~~~~ 朋友的朋友的朋友
最佳解答:
(1) Let X = 餅, Y = 芝士腸, Z = 香蕉 Let A: 2X 1Y ---> 2Y 2Z Let B: 1X 2Y ---> 3Z We have: 5X 2Y ----(B)----> 3X 3Y 3Z ----(A)----> 1X 4Y 6Z ----(B)----> 2Y 9Z Therefore, 9 隻香蕉 *********************************** (2) Let x = 甲今年的年齢, y = 乙今年的年齢 x = 7y ................................................(1) x+a = 6(y+a) ......................................(2) x+b = 5(y+b) ......................................(3) x+c = 4(y+c) ......................................(4) x+d = 3(y+d) ......................................(5) x+e = 2(y+e) ......................................(6) where 0 < a < b < c < d < e. Put (1) into (2), 7y+a = 6y+6a y = 5a x = 35a You may go on solving the equation if you like, but I would use the method of inspection here. x = 35 or 70 (135+ not likely for ages) This year: x=35, y=5 2st year: x=36, y=6 5th year: x=40, y=10 10th year: x=45, y=15 25th year: x=60, y=30 Therefore 甲今年的年齢 = 35 2007-05-26 01:16:44 補充： Sorry, for (1) should be:5X 2Y ----(A)----> 3X 3Y 2Z ----(A)----> 1X 4Y 4Z ----(B)----> 2Y 7Z7隻香蕉
其他解答:
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