If `r^(th)` term is the middle term in the expansion of `(x^2-1/(2x))^20`, then `(r+3)^(th)` term is

Explanation

Here `n` is evenL

So, The middle term in the given expansion is `(frac{20}{2}+1)` th `=11` th term

Therefore, `(r+3)` th term is the 14 th term.

`T_{14}=\ ^{20} C_{13}(x^{2})^{20-13}(frac{-1}{2 x})^{13} `

`=(-1)^{1320} C_{13} frac{x^{14-13}}{2^{13}} `

`=-\ ^{20} C_{7} x 2^{-13}`