Moderate -0.5 This is a straightforward application of the binomial expansion requiring factoring out the constant (4) first, then expanding (1 + x/2)^(1/2). While it requires understanding of the generalised binomial theorem and validity conditions, it's a standard textbook exercise with no novel problem-solving required, making it slightly easier than average.
2 Find the first 4 terms in the binomial expansion of $\sqrt { 4 + 2 x }$. State the range of values of $x$ for which the expansion is valid.
\hfill \mbox{\textit{OCR MEI C4 2005 Q2 [6]}}