1.

In the expansion of `[(1+x)//(1-x)]^2,`the coefficient of `x^n`will be`4n`b. `4n-3`c. `4n+1`d. none of theseA. `4n`B. `4n-3`C. `4n+1`D. none of these

Answer» Correct Answer - A
Given term can be written as
`(1+x)^(2)(1-x)^(-2)=(1+2x+x^(2))[1+2x+3x^(2)+"....."+(n-1)xxx^(n-2)+nx^(n-1)+(n+1)x^(n)+"...."oo]`
Coefficient of `x^(n)` is `(n+1+2n+n-1)=4n`.


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