Edexcel AS Paper 1 2018 June — Question 11

Exam BoardEdexcel
ModuleAS Paper 1 (AS Paper 1)
Year2018
SessionJune
TopicBinomial Theorem (positive integer n)
TypeProduct with unknown constant to determine

  1. (a) Find the first 3 terms, in ascending powers of \(x\), of the binomial expansion of
$$\left( 2 - \frac { x } { 16 } \right) ^ { 9 }$$ giving each term in its simplest form. $$f ( x ) = ( a + b x ) \left( 2 - \frac { x } { 16 } \right) ^ { 9 } , \text { where } a \text { and } b \text { are constants }$$ Given that the first two terms, in ascending powers of \(x\), in the series expansion of \(\mathrm { f } ( x )\) are 128 and \(36 x\),
(b) find the value of \(a\),
(c) find the value of \(b\).