f.3 maths pls help !

leung

2014-09-16 2:38 am

If m is an integer ,simplify [64 ^(2m-3) ] / [ 16^(5m)]

我知ans is :

2^(-8m-18)

我想問點解(^-8m-18) 有 negative ,不用把整個數再倒轉,即 1/( 2^8m *2^18)

???

回答 (2)

MintyB

2014-09-16 2:48 am

✔ 最佳答案

Formula:
1/(x^m) = x^(-m)

64^(2m-3)/16^(5m)
=2^[6(2m-3)]/2^[4(5m)]
=2^(12m-18-20m)
=2^(-8m-18)

2014-09-15 19:05:45 補充：
如果你想把它倒轉變份數也可.

2014-09-16 03:03:51 補充：
Formulas:
(a^m)^n = a^(mn)...........................(i)
((-a)^m)^n)=(-a)^(mn).....................(ii)

[-3^(-2)]^(-7)
=-3^[-2*(-7)]
=-3^14

由，你應可自行解答: (-10)^(-1 ),不用乘 -10 個負 ??

說出你的答案來讓我看看
:-)

2014-09-16 03:26:17 補充：
上句有D字唔見咗，應該是:
由上面formula(ii)，你應可自行解答: (-10)^(-1 ),不用乘 -10 個負 ??

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[匿名]

2014-09-16 9:29 am

ASK YOUR TEACHER!!!!!!!!!!!!!!!

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