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7.Binomial Theorem
easy
In the expansion of ${\left( {2{x^2} - \frac{1}{x}} \right)^{12}}$, the term independent of x is
A
$10^{th}$
B
$9^{th}$
C
$8^{th}$
D
$7^{th}$
Solution
(b) ${T_{r + 1}} = {}^{12}{C_r}{(2{x^2})^{12 – r}}{( – 1)^r}{\left( {\frac{1}{x}} \right)^r}$
For term independent of $x$,
$24 – 3r = 0 \Rightarrow r = 8$ So, $9^{th}$ term independent of $x$.
Standard 11
Mathematics