Moderate -0.5 This is a straightforward application of the binomial theorem requiring identification of the correct term and solving a simple equation. While it involves a reciprocal term that students must handle carefully, it's a standard textbook exercise with no conceptual difficulty beyond basic binomial expansion mechanics.
The coefficient of $x^2$ in the expansion of $\left(k + \frac{1}{x}\right)^5$ is 30. Find the value of the constant $k$. [3]
\hfill \mbox{\textit{CAIE P1 2011 Q1 [3]}}