7.Binomial Theorem
hard

The term independent of ' $x$ ' in the expansion of $\left(\frac{x+1}{x^{2 / 3}-x^{1 / 3}+1}-\frac{x-1}{x-x^{1 / 2}}\right)^{10}$, where $x \neq 0,1$ is equal to $.....$

A

$110$

B

$210$

C

$300$

D

$400$

(JEE MAIN-2021)

Solution

$\left(\left(x^{1 / 3}+1\right)-\left(\frac{x^{1 / 2}+1}{x^{1 / 2}}\right)\right)^{10}$

$=\left(x^{1 / 3} \frac{1}{x^{1 / 2}}\right)^{10}$

Now General Term

$\mathrm{T}_{\mathrm{r}+1}={ }^{10} \mathrm{C}_{r}\left(\mathrm{x}^{1 / 3}\right)^{10-\mathrm{r}} \cdot\left(-\frac{1}{\mathrm{x}^{1 / 2}}\right)^{\mathrm{r}}$

For independent term

$\frac{10-r}{3}-\frac{r}{2}=0 \Rightarrow r=4$

$\Rightarrow T_{5}={ }^{10} C_{4}=210$

Standard 11
Mathematics

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