Find the first four terms, in ascending powers of xxx, of the binomial expansion of 1+kx \sqrt{1 + kx}\,1+kx giving each term in its simplest form.
Explain how you could use x=112\displaystyle x = \frac{1}{12}x=121 in the expansion to find an approximation for 1+k12\displaystyle \sqrt{1 + \frac{k}{12}}1+12k. There is no need to carry out the calculation.
408 exam-style questions on Edexcel A Level Maths Binomial Expansion, covering 4.1 Expanding (1 + x)^n, 4.2 Expanding (a + bx)^n, and 4.3 Using Partial Fractions. Each one has a worked solution and a mark scheme showing where the marks go.