A Level

MATHEMATICS · Multi-part · A Level · Mathematics · Sequences and series · Sequences and series

Problem

Find (1) (i) the coefficient of

x^7

in the expansion of

\left(ax^2 + \frac{1}{bx}\right)^{11}

. (2) (ii) the coefficient of

x^{-7}

in the expansion of

\left(ax - \frac{1}{bx^2}\right)^{11}.

(3) Also, find the relation between

a

and

b

, so that these coefficients are equal.