The coefficient of t^{4} the expansion of is

The coefficient of t^{4} the expansion of is

1 Answer

127 votes

(1−t^{6})^{3}(1−t) ^{−3}

(1−t^{18}−3t^{6}+3t^{12})(1−t)^{−3} is

cofficient of t^{4} in (1−t) ^{−3} is

^{3+4−1}C_{4}=^{6}C_{2}=15

127 votes

127