Answer
$126x^5$
Work Step by Step
Calculate the fifth term for $(x-1)^{9}$. by using General formula such as:$(m+n)^r=\displaystyle \binom{r}{k}m^{r-k}n^k$
and $\displaystyle \binom{r}{k}=\dfrac{r!}{k!(r-k)!}$
This implies,
$(x-1)^{9}=\displaystyle \binom{9}{4}(x)^{9-4}(-1)^4$
This implies,
or, $=\dfrac{9!}{4!(9-4)!}[x^{5}(-1)^4]$
or, $=[\dfrac{9 \times 8 \times 6 \times 5!}{4 \times 3 \times 2 \times 1(5!)}]x^{5}$
or,$=126x^5$
