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奧數有幾題唔識做...
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1. let father aged x , and son aged y , then x=5y and (x+18)=2(y+18) =>x=5y and x=2y+18 =>5y=2y+18 =>3y=18 =>y=6 and x=5y=5*6=30// 2. let the date of that satuaday is x and as we know , one month has 4 weeks , then the dates are x , x+7 ,x+14 , x+28 =>x+x+7+x+14+x+21 = 54 =>4x+42=54 =>x=3 // 2010-02-05 23:14:37 補充： 4. x^3-1/x^3 =(x-1/x)[x^2+(x)(x/x)+(1/x)^2] =x^2+1+1/x^2 =x^2-2+1/x^2+3 =x^2-2(x)(1/x)+(1/x)^2+3 =(x-1/x)^2+3 =1+3 =4//
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奧數有幾題唔識做...
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此文章來自奇摩知識+如有不便請留言告知
1.父親今年的年齡是兒子的5倍，再過18年，父親的年齡是兒子年齡的2倍，那麼父親今年是幾歲？ 2.某年4月所有星期六的日期數之和是54，這年4月的第一個星期六的日期數是什麼？ 3.http://img205.imageshack.us/img205/3125/65383934.gif 4.http://img697.imageshack.us/img697/738/74066137.png 更新: 第三條你不懂嗎...?那條是計算佢的值。最佳解答:
1. let father aged x , and son aged y , then x=5y and (x+18)=2(y+18) =>x=5y and x=2y+18 =>5y=2y+18 =>3y=18 =>y=6 and x=5y=5*6=30// 2. let the date of that satuaday is x and as we know , one month has 4 weeks , then the dates are x , x+7 ,x+14 , x+28 =>x+x+7+x+14+x+21 = 54 =>4x+42=54 =>x=3 // 2010-02-05 23:14:37 補充： 4. x^3-1/x^3 =(x-1/x)[x^2+(x)(x/x)+(1/x)^2] =x^2+1+1/x^2 =x^2-2+1/x^2+3 =x^2-2(x)(1/x)+(1/x)^2+3 =(x-1/x)^2+3 =1+3 =4//
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