# Binomial expansion

## Binomial expansion

Given that the binomial expansion of $\left&space;(&space;1+kx&space;\right&space;)^{-4},\hspace{0.5&space;cm}&space;\left&space;|kx&space;\right&space;|<&space;1,$ is

$1-6x+Ax^2+\cdots$

(a) find the value of the constant k,

(b) find the value of the constant A, giving your answer in its simplest form.

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