F.3 Maths Exam QQ Urgent.....

2^(n – 1) + 2^n
--------------------------
3 . 2^(n + 1)

2^n . 2^(-1) + 1. (2^n)
--------------------------------
3 . (2^n) . (2^1)


2^n (1/2) + 1. 2^n
--------------------------
3 . (2^n) . ( 2)


2^n [ (1/2) + 1]
--------------------------
(2 x 3) . 2^n .

cancel the term 2^n in both numerator and denominator

[ (1/2) + 1]
--------------------
6

(1 1/2)/6
(3/2)/ (6)

1/4 ~ Answer

Note:
You have to know that
2^(m + n) = (2^m) x (2^n)
2^n = 1 x (2^n)
2^(-1) = 1/(2^1) = 1/2

x = multiplication sign,

2013-12-17 04:14:39 補充：
Another way:
2^(n – 1) = (2^n) / (2^1)
=2^n / 2
=( 2^n ) (1/2)

答案在此，有不明白的地方請提出：
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