Past Papers’ Solutions  Edexcel  AS & A level  Mathematics  Core Mathematics 1 (C16663/01)  Year 2013  June  Q#4
Question
A sequence is defined by
, for
Where is a constant.
a) Find an expression for in terms of k.
Given that ,
b) Find the two possible values of k.
Solution
a)
We are given that sequence is defined by
We are required to find .
We can utilize the given expression for general terms beyond first term as;
b)
We are given that;
It is evident that sum of first 3 terms of given arithmetic sequence is 2.
We are already given first term and have found 2^{nd} term in (a) while we need to find 3^{rd} term.
We can utilize the given expression for general terms beyond first term as;
We can substitute from (a);
Therefore;
As per given condition ;
Now we have two options.









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