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If `(1 +x+x^2)^n=sum_(r=0)^(2n) a_r x^r` , then prove that `a_r=a_(2n-r)`A. `n+1`B. `r+1`C. `n+r+1`D. `n+r` |
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Answer» Correct Answer - C Coeff. `X^(3r)` in `[(1+x+x^(2))^(n)(1-x)^(n)]` `implies` coeff. of `x^(3r)` in `[(a_(0)+a_(1)x+…a_(2)x^(2n))(n_(c_(0))-n_(c_(1)) xx……)]` `.^(n)C_(r)` |
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