數學題１條．．．

(a)
T(1) = 1
T(2) = 1 + 3
T(3) = 1 + 3 + 4
T(4) = 1 + 3 + 4 + 5
...
In general, it can be noted that
T(n)
= [1 + 2 + 3 + 4 + ....... + (n+1)] - 2 for n = 1,2,3,....
= [(n+1)(n+2)]/2 - 2
= (n^2 +3n - 2)/2

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(b)
T(n) = 2^(n+1) - (n+5)

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(c)
It can be imagined as a sequence on the number line oscillating from 1 with an increasing magnitude.

因為好難就咁打出黎，
係係一畫家到畫左出黎
http://i155.photobucket.com/albums/s312/umin08277/maths.jpg
希望可以幫到他la~