1.

Write the coefficient of `x^(7) y^(2)` in the expansion of `(x+2y)^(9)`.A. Least value `-1/4`B. Least value `-9/4`C. Greatest value `1/4`D. Greatest value `9/4`

Answer» Correct Answer - 144
`T_(r+1)= .^(9) C _(r)x^(9-r) * (2y)^(r) = .^(9)C_(r) xx 2^(r) xx x^((9-r)) xx y^(r).`
Putting ` r = 2, " we get the coefficient of " x^(7) y^(2) " as " .^(9) C_(2) xx 2^(2) = 144.`


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