用简便方法计算下面各题(1) 1/12÷1/4+11/12+3/4 (2) 29/30-1/6+1/30÷1/6 (3)

1个回答

  • 1/12 / 1/4 + 11/12 + 3/4

    = 1/12 X 4 + 8/12 + 3/12 + 3/4

    = 4/12 + 8/12 + 1/4 + 3/4

    = 12/12 + 4/4

    = 2

    29/30 - 1/6 + 1/30 / 1/6

    = 24/30 + 5/30 - 1/6 + 1/30 X 6

    = 24/30 + 1/6 - 1/6 + 6/30

    = 30/30

    = 1

    ( 12/21 / 5/7 ) X ( 12/25 / 4/5 )

    = 12/21 X 7/5 X 12/25 X 5/4

    = ( 12 X 7 X 12 X 5 ) / ( 21 X 5 X 25 X 4 )

    = ( 12 X 7 X 3 X 4 X 5 ) / ( 7 X 3 X 5 X 4 X 25 )

    = 12/25

    或者

    = [ ( 21 X 12/21 ) / ( 5/7 X 21 ) ] X [ ( 25 X 12/25 ) / ( 4/5 X 25 ) ]

    = [ 12 / ( 5 X 3 ) ] X [ 12 / ( 4 X 5 ) ]

    = 4/5 X 3/5

    = 12/25

    5/17 / 9 + 1/9 X 4/17

    = 5/17 X 1/9 + 1/9 X 4/17

    = 1/9 X 9/17

    = 1/17