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Re: 28-13

by gabriel » Thu Aug 30, 2007 10:44 am
magical cook wrote:Hi, Can anyone help? thanks
when n=5 , a(n)= a(5) which is equal to 2a(4)-X .. but a(4) = 2a(3)-X, substituting this value of a(4) in the previous equation we get .. a(5) = 2(2a(3)-X)-X = 4a(3)-3X ..

Now, a(5)= 99 and a(3)= 27 ..

SO, 99= 4*27-3X---> 3X = 9 .. so X = 3 ..
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by magical cook » Thu Aug 30, 2007 12:27 pm
Thank you:)
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