Past Papers’ Solutions | Edexcel | AS & A level | Mathematics | Core Mathematics 1 (C1-6663/01) | 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 2nd term in (a) while we need to find 3rd 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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