MCQ
The number of terms whose values depends on x in the expansion of $\Big(\text{x}^{2}-2+\frac{1}{\text{x}^{2}}\Big)^{\text{n}}$ is:
  • A
    2n + 1
  • 2n
  • C
    n
  • D
    None of these

Answer

Correct option: B.
2n
  1. 2n
Solution:
$\Big(\text{x}^{2}-2+\frac{1}{\text{x}^{2}}\Big)^{\text{n}}$
$=\Big[\big(\text{x}-\frac{1}{\text{x}}\big)^{2}\Big]^{\text{n}}$
$=\big(\text{x}-\frac{1}{\text{x}}\big)^{{2}\text{n}}$
Hence there will be $2 \mathrm{n}+1$ terms.
The middle term i.e $\mathrm{n}+1^{\text {th }}$ term will be independent of x .
Hence total number of terms, dependent on x will be
$2 n+1-(1)$
$=2 n \text { terms. }$

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