(+2)×(-10)÷(+4)×(-5)

(+2)×(-10)÷(+4)×(-5)
=(+-2×10)÷(+-4×5)
=(-20)÷(-20)
=--(20÷20)
=1
本題為方便表示+-關係才寫「+-」和「--」，我不建議香港人這樣寫。

2008-09-24 14:39:37 補充：
記得有人話愈容易愈是危險
看來本人計錯
(+2)×(-10)÷(+4)×(-5)
按計算機後出25
正確是
(+2)×(-10)÷(+4)×(-5)
= +-20 ÷ ( +4) x ( -5)
= (-5)x (+-5 )
= (-5)x (-5 )
= --(5x5 )
= 25

(+2)×(-10)÷(+4)×(-5)
=-20÷(+4)*(-5)
=-5*(-5)
=+25

(+2)×(-10)(+4)×(-5)
=(-20)÷(+4)×(-5)(負正得負)
=(-5)×(-5)(負正得負)
=25(負負得正)

(+2)x(-10)÷(+4)x(-5)

= (- 20) ÷ (- 20) < 正負得負>

= 1 < 負負得正 >

希望可以幫到你 ^^

2008-09-20 14:29:18 補充：
- 0 -睇錯左 .. s0r ...

(+2)x(-10)÷(+4)x(-5)

= -20 ÷ ( +4) x ( -5) << -20 ___ < 正負得負>>

= (-5)x (-5 ) << (-5) ___ < 負正得負>>

= 25 << 25___<負負得正>>

(-20)÷(+4)×(-5)

-5 x (-5)

=25

2008-09-20 14:16:59 補充：
(+2)×(-10)÷(+4)×(-5)

(-20)÷(+4)×(-5)

-5 x (-5)

=25