i need help with binomial expansion pls, the question is attached

Answer:
[tex] \\\left(a + b\right)^{n} = \\ \sum_{k=0}^{n} {\binom{n}{k}} a^{n - k} b^{k} \\ \left(2 - 9 x\right)^{4} = \\ 16 - 288 x + 1944 x^{2} \\ - 5832 x^{3} + 6561 x^{4} \\ = 16 - 288 x + 1944 x^{2}\\ A - 232 x + B x^{2} \\ \therefore A=16 \\ (1+kx)(16 - 288 x + 1944 x^{2})\\ 16kx -288x =-232x \\ 16k=56 \\ \therefore k=\frac{7}{2}\\ B =1944-288( \frac{7}{2} )\\\therefore B=936[/tex]
All you have to do is compare coofficients...