In using the binomial formula, we let

`text(")atext(")=2a,` `b=-1/x` and `n=11`.

Substituting in the binomial formula, we get:

`(2a-1/x)^11`

`=(2a)^11+11(2a)^10(-1/x)` `+(11(10))/(2!)(2a)^9(-1/x)^2` `+(11(10)(9))/(3!)(2a)^8(-1/x)^3+...`

`=2048a^11-11264(a^10)/x` `+28160(a^9)/(x^2)-42240(a^8)/(x^3)+...`