Work out the first three terms in the binomial expansion of (1+3x)12\displaystyle (1 + 3x)^{\frac{1}{2}}(1+3x)21.
Write down the range of values of x x\,x for which the expansion is valid.
308 exam-style questions on AQA A Level Maths 1.7 D: Sequences and series, covering 1.7.1 Binomial expansion, 1.7.2 Types of sequence (A-level only), 1.7.3 Sigma notation (A-level only), 1.7.4 Arithmetic sequences and series (A-level only), 1.7.5 Geometric sequences and series (A-level only), and 1.7.6 Sequences and series in modelling (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.