我唔係好識有向數

1. (+71) - (+23)
= 71 - 23
= 48

2. (-45) + (-6)
= - 51

3. (-83) + (+27)
= (-83) + 27
= - 56

4. (+2.1) - (+6.3)
= 2.1 - 6.3
= -4.2

5. (-3)+(+1)-(+9)
= -3 + 1 - 9
= -2 - 9
= -11

6.(+5)+(-7)-(-11)
= 5 - 7 + 11
= -2 + 11
= 9

記得 :

負負得正
負正得負
正負得負
正正得正

2007-10-28 19:42:05 補充：
我想問下你是明還是不明 ?憑這句句子:' 我真係好明呀 '' 我唔係好識有向數 '

1.)(+71) -(+23) =71 - 23 = 48 ( 一 + = 一)

2.)(-45) +(-6) = - 45 - 6 = -51 ( + - = -)

3.)(-83) +(+27)= - 83 + 27= - 56 ( + + =+)

4.)(+2.1) -(+6.3)= 2.1 - 6.3 = -4.2 ( - + = - )

5.)(-3)+(+1) -(+9) = -3 + 1 - 9 = - 11 ( - + = - )

6.)(+5)+(-7) -(-11) = 5 - 7 +11= 9 ( - - = + )