Find the first 4 terms, in ascending powers of xxx, of the binomial expansion of (1+ax)10(1 + ax)^{10}(1+ax)10, where a a\,a is a non-zero constant. Give each term in its simplest form.
Given that, in this expansion, the coefficient of x3 x^3\,x3 is double the coefficient of x2x^2x2, find the value of aaa.
10 exam-style questions on Edexcel A Level Old Maths The Binomial Expansion. Each one has a worked solution and a mark scheme showing where the marks go.