Edexcel C2 — Question 7

Exam BoardEdexcel
ModuleC2 (Core Mathematics 2)
TopicBinomial Theorem (positive integer n)
TypeFirst few terms given find parameters

  1. The first four terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 + k x ) ^ { n }\) are
$$1 + A x + B x ^ { 2 } + B x ^ { 3 } + \ldots$$ where \(k\) is a positive constant and \(A\), \(B\) and \(n\) are positive integers.
  1. By considering the coefficients of \(x ^ { 2 }\) and \(x ^ { 3 }\), show that \(3 = ( n - 2 ) k\). Given that \(A = 4\),
  2. find the value of \(n\) and the value of \(k\).
    7. continuedLeave blank