標題:
一條好簡單但係又計唔到既數
發問:
己知X^2=YZ 和W=Y-Z 證明X=W
最佳解答:
點解好似計唔到咁既... 代d數入去... Suppose X = W = 2, Y = 1, Z = 4 is ture. Case 1 X^2 = 2^2 = 4 = 1 X 4 = YZ Case 2 W = Y - Z = 1 - 4 = -3 not equal to X Contradiction!!!!! therefore, X is not equal to W... /.\ 2007-02-14 12:38:34 補充： Re: chaoseng2000 [小學級 5 級]你講既全部都係假設... 仲未有結論....因為你只係假設 X=W...到最後都係冇證明到 X=W"所以你個結論都係一個假設..."唔成立...
其他解答:
因為x=w時 ==>w^2=yz 而w=y-z ==>w^2=y^2-2yz+z^2 即yz=y^2-2yz+z^2 y^2-3yz+z^2=0 ==>y=[3+5^(1/2)]z/2或y=[3-5^(1/2)]z/2 即當y=[3+5^(1/2)]z/2或y=[3-5^(1/2)]z/2時命題x=w才成立|||||X^2=YX------(1) W=Y-Z--------(2) (1)W^=Y^2-2YZ+Z^2 . . . 計到這裏 以經計不到|||||因為一條計唔到既數可以好簡單。
一條好簡單但係又計唔到既數
發問:
己知X^2=YZ 和W=Y-Z 證明X=W
最佳解答:
點解好似計唔到咁既... 代d數入去... Suppose X = W = 2, Y = 1, Z = 4 is ture. Case 1 X^2 = 2^2 = 4 = 1 X 4 = YZ Case 2 W = Y - Z = 1 - 4 = -3 not equal to X Contradiction!!!!! therefore, X is not equal to W... /.\ 2007-02-14 12:38:34 補充： Re: chaoseng2000 [小學級 5 級]你講既全部都係假設... 仲未有結論....因為你只係假設 X=W...到最後都係冇證明到 X=W"所以你個結論都係一個假設..."唔成立...
其他解答:
因為x=w時 ==>w^2=yz 而w=y-z ==>w^2=y^2-2yz+z^2 即yz=y^2-2yz+z^2 y^2-3yz+z^2=0 ==>y=[3+5^(1/2)]z/2或y=[3-5^(1/2)]z/2 即當y=[3+5^(1/2)]z/2或y=[3-5^(1/2)]z/2時命題x=w才成立|||||X^2=YX------(1) W=Y-Z--------(2) (1)W^=Y^2-2YZ+Z^2 . . . 計到這裏 以經計不到|||||因為一條計唔到既數可以好簡單。
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