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Question
If rth term is the middle term in the expansion of \[\left( x^2 - \frac{1}{2x} \right)^{20}\] then \[\left( r + 3 \right)^{th}\] term is
Options
\[^{20}{}{C}_{14} \left( \frac{x}{2^{14}} \right)\]
\[^{20}{}{C}_{12} x^2 2^{- 12}\]
- \[- ^t{20}{}{C}_7 x, 2^{- 13}\]
none of these
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Solution
So, The middle term in the given expansion is
`= \left( - 1 \right)^{13} "^20C_{13} \frac{x^{14 - 13}}{2^{13}}`
\[ = - ^{20}{}{C}_7 x 2^{- 13}\]
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