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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 6: 31/2*32/2*33/2*…*60/2=a CMR a=1*3*5*…*59

Toán Lớp 6: 31/2*32/2*33/2*…*60/2=a CMR a=1*3*5*…*59

Comments ( 2 )

  1. Ta có : 
    A=\frac{31.32.33…60}{2.2.2…2}
    =\frac{(1.2.3.4…30)(31.32.32…60)}{(1.2.3.4…30)(2.2.2….2)}
    =\frac{(1.3.5……59)(2.4.6….60)}{(1.2)(2.2)(3.2)….(30.2)}
    =\frac{(1.3.5……59)(2.4.6….60)}{2.4.6…60}
    =1.3.5…99   

  2. Ta có : A = 31/2 . 32/2 . 33/2 ….. 60/2
    A = ( 31 . 32 . 33 ….. 60 )/( 2 . 2 ….. 2 )
    A = ( ( 1 . 2 . 3 ….. 30 ) . ( 31 . 32 . 33 …. 60 ) )/( ( 1 . 2 . 3 ….. 30 ) . ( 2 . 2 ….. 2 ) )
    A = ( ( 1 . 3 . 5 …… 59 ) . ( 2 . 4 . 6 ….. 60 ) )/( ( 1 . 2 ) . ( 2 . 2 ) . ( 3 . 2 ) …. ( 30 . 2 ) )
    A = ( ( 1 . 3 . 5 …… 59 ) . ( 2 . 4 . 6 ….. 60 ) )/( 2 . 4 . 6 ….. 60 )
    A = 1 . 3 . 5 …… 59 ( Điều phải chứng minh )

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222-9+11+12:2*14+14 = ? ( )

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