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Sum of the coefficients of terms of degree 13 in the expansion of`(1+x)^(11) (1+y^(2)-z)^(10)` isA. `.^(10)C_(3)`B. `.^(10)C_(4)`C. `.^(11)C_(3)`D. `.^(11)C_(4)` |
Answer» Correct Answer - B Required sum of coefficient `=` coefficient of `t^(15)` in `(1+t)^(11) (1+t^(2) - t)^(100)` `=` coefficeint of `t^(13)` in `(1+t)(1+t^(3))^(10)` `=` coefficient of `t^(13)` in `((1+t^(3))^(10) + t(1+t^(3))^(10))` `=` coefficient of `t^(12)` in `(1+t^(3))^(10)` `= .^(10)C_(4)` |
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