各位知識朋友 , 入黎幫我手 ar !!! ( 數學F.1 ) (11)

1) (+28)÷(+4)×(-7)
=(+7)×(-7)
=-49

2) (-5)÷(-1∕3)÷(+3∕4)×(-2)
=(+15)÷(+3∕4)×(-2)
=20×(-2)
=-40

2007-09-16 11:47:46 補充：
樓上那位人兄第2題計錯數!!!因為除數沒有交換性質,所以應該順序計下去!!!

2007-09-16 11:50:38 補充：
原來第1題都犯了同樣的錯誤啊!!!

2007-09-16 11:51:26 補充：
走左....

1)
=7x(-7)
=-49
2)
=15÷3/4x(-2)
=20x(-2)
= - 40

1.

28 28
--- = --- = -1
4X(-7) -28

2.
-5÷(-1∕3)÷(+3∕4)×(-2) = 15÷ -3 = -10
---
2

(+28)÷(+4)×(-7)
=7×(-7)
=-49

(-5)÷(-1∕3)÷(+3∕4)×(-2)
=15÷(+3∕4)×(-2)
=20×(-2)
=-40

信我!一定岩!先乘除後加減嘛

第二個先係正確

1. 28 / 4 x (-7)
=7x(-7)
= - 49

2. (-5) x (-3) x 4/3 x -2
=(-5) x (-4) x (-2)
= - 40