sequence

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sequence

by datonman » Tue Aug 25, 2015 10:54 am
I wasn't sure how to put it in microsoft word format so I uploaded the question which i took from the book. Obviously I know what the answer is but i was wondering if there was another way to solve this particular question.
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by DavidG@VeritasPrep » Tue Aug 25, 2015 11:26 am
Picking numbers is a nice simple way to attack sequence questions. Let's start by setting n = 2, so that we can find x2. If we plug '2' into our equation, we get:
x2 = 2*x1 - (1/2)x0

We're given x0 = 3 and x1 = 2.

So let's substitute '2' in place of x1 and '3' in place of x0 and we'll have:

x2 = 2*2 - (1/2) * 3 = 4 - (3/2) = 5/2.

If we set n = 3, to find x3, we'll get:
x3 = 2*x2 - (1/2)x1

We know that x2 = 5/2 and we know that x1 = 2. So
x3 = 2*(5/2) - (1/2)*2 = 5 - 1 = 4.

Answer is C
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