SPS SPS FM 2023 October — Question 5 6 marks

Exam BoardSPS
ModuleSPS FM (SPS FM)
Year2023
SessionOctober
Marks6
TopicBinomial Theorem (positive integer n)
TypeCoefficient relationship between terms
DifficultyModerate -0.8 This is a straightforward binomial expansion question requiring recall of the binomial theorem for n=3, followed by a simple algebraic equation. Part (i) is routine manipulation, and part (ii) involves equating two terms and solving a quadratic—both are standard textbook exercises with no problem-solving insight required. The low power (n=3) and direct application make this easier than average.
Spec1.04a Binomial expansion: (a+b)^n for positive integer n

  1. Find the binomial expansion of \((3 + kx)^3\), simplifying the terms. [4]
  2. It is given that, in the expansion of \((3 + kx)^3\), the coefficient of \(x^2\) is equal to the constant term. Find the possible values of \(k\), giving your answers in an exact form. [2]

\begin{enumerate}[label=(\roman*)]
\item Find the binomial expansion of $(3 + kx)^3$, simplifying the terms. [4]
\item It is given that, in the expansion of $(3 + kx)^3$, the coefficient of $x^2$ is equal to the constant term. Find the possible values of $k$, giving your answers in an exact form. [2]
\end{enumerate}

\hfill \mbox{\textit{SPS SPS FM 2023 Q5 [6]}}