# Past Papers’ Solutions | Edexcel | AS & A level | Mathematics | Core Mathematics 1 (C1-6663/01) | Year 2013 | January | Q#4

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**Question**

A sequence satisfies

, ,

Given that ,

**a) **Find the value of and the value of .

**b) **Evaluate .

**Solution**

**a) **

We are given that sequence is defined by

We are given that and required to find .

We can utilize the given expression for general terms beyond first term as;

Similarly, we can find .

**b) **

We are required to find;

It is evident that we are required to find sum of first 4 terms.

We have already found 3^{rd} and 4^{th }terms and are given 2^{nd} terms in (a). We need to find 1^{st} term.

Hence;

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