The expansion of (1+kx)n(1+kx)^n(1+kx)n, where k k\,k and n n\,n are constants and n n\,n is not an integer, in ascending powers of x x\,x up to and including x3 x^3\,x3 is
1+x−x2+53x3. 1+x-x^2+\frac{5}{3}x^3. 1+x−x2+35x3.Find the value of k k\,k and the value of nnn, and state the set of values of x x\,x for which the expansion is valid.
Use this expansion to find an approximation for 1.123\sqrt[3]{1.12}31.12 to 5 decimal places.
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.