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If (1+2x+x^2)^n=sum(r=0)^(2n)ar x^r ,the...

If `(1+2x+x^2)^n=sum_(r=0)^(2n)a_r x^r` ,then `a_r ` is a.`(.^nC_2)^2` b. `.^n C_r .^n C_(r+1)` c. `.^(2n) C_r` d. `.^(2n) C_(r+1)`

A

`(""^(n)C_(r))^(2)`

B

`""^(n)C_(r)*""^(n)C_(r+1)`

C

`""^(2n)C_(r)`

D

`""^(2n)C_(r+1)`

Text Solution

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The correct Answer is:
C
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