Question

Is my process (binomial theorem) correct?

Answer 1

Q1: Find the ninth tenth of this bonomial \[(x-\frac{ 1 }{ x })^{12}\]
So n=12, and r=9-1=8

Answer 2

\[\left(\begin{matrix}12 \\ 8\end{matrix}\right)a ^{4}b ^{8}\]

Answer 3

\[\frac{ 8!\times9\times10\times11\times12 }{ 8!\times2\times3\times4 }\]

Answer 4

\[495\left( x ^{4} \right)\left( \frac{ 1 }{ x ^{8} } \right)\]=\[495x ^{-4}\]

Correct?