In the binomial expansion of (1+bx)n(1 + bx)^n(1+bx)n, where n n\,n is a rational number and b b\,b is a positive constant, the coefficient of x x\,x is 6 and the coefficient of x2 x^2\,x2 is -18.
Show that n=12\displaystyle n = \frac{1}{2}n=21 and find the value of bbb.
State, using set notation, the range of values of x x\,x for which the expansion is valid.
Find the coefficient of x3 x^3\,x3 in the expansion.
231 exam-style questions on WJEC A Level Maths 3.4 Sequences and Series (A-level only), covering 3.4.1 Sequences and Series (A-level only), 3.4.2 Sequences and Series (A-level only), 3.4.3 Sequences and Series (A-level only), 3.4.4 Sequences and Series (A-level only), 3.4.5 Sequences and Series (A-level only), 3.4.6 Sequences and Series (A-level only), and 3.4.7 Sequences and Series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.