Past Papers’ Solutions | Cambridge International Examinations (CIE) | AS & A level | Mathematics 9709 | Pure Mathematics 1 (P1-9709/01) | Year 2007 | Oct-Nov | (P1-9709/01) | Q#3

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Question


i.       
Find the first three terms in the expansion of in ascending powers of .

   ii.       Use the substitution in your answer to part (i) to find the coefficient of  in the expansion of .

Solution


i.
 

Expression for the Binomial expansion of  is:

In the given case:

Hence;


ii.
 

Substituting  in 

Gives us

We are interested only in coefficient of terms with :

The only terms with :

Hence coefficient of  is .

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