Series Question (1 Viewer)

trungduong12 · Jun 25, 2014

This is a question in the test i just did today
I found it quite hard since the series given is not AP or GP
I dont know how to start this question
;(

Please help me !!!

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integral95 · Jun 25, 2014

Haha nice question,

This actually consists of BOTH AP and GP

First you separate the series into 2 parts , the sum of the first 20 terms in (n-1)

i.e $(0-1-2-3-....-19) = 20/2(0-19) = -190$

then I find the sum of the first 20 terms in $2^n$ which is

$2+ 2^2 +2^3 + ... 2^{20} = 2(2^{20} -1)$

Adding those two will give you the answer

Series Question (1 Viewer)

trungduong12

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integral95

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