求下列各數式的值

2010-12-25 12:08 am
(a)-7+(-13)+14+(+12)
(b)9x(-4)+(-2)x(-3)

回答 (3)

2010-12-25 12:18 am
✔ 最佳答案
They are typical S.1 questions. Answers as follow:

(a) -7 + ( -13 ) + 14 + ( +12 )
= -7 - 13 + 14 + 12
= 14 + 12 - 7 - 13
= 26 - 20
= 6

(b) 9( -4 ) + ( -2 )( -3 )
= -36 + 6
= 6 - 36
= -30

What you need to get familiar are:

(+)(+) = (+), (-)(+) = (-), (+)(-) = (-) and (-)(-) = (+).

Hope I have helped you.
參考: Mathematics Teacher Mr. Ip
2010-12-25 5:08 am
-7+(-13)+14+(+12)
=-7-13+14+12
=14+12-7-13
=26-20
=6
9*(-4)+(-2)*(-3)
=-(9*4)+(2*3)
=-36+6
=6-36
=-30
參考: 膠人至上
2010-12-25 2:01 am
a.
-7+(-13)+14+(+12)
=-7-13+14+12
=14+12-7-13
=26-20
=6
-------------------------------------------
b.
9x(-4)+(-2)x(-3)
=-36+6
=6-36
=-30
參考: 肥龍


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