Find the two middle terms of `(3x - (x^3)/6)^9`

Find the middle terms in the expansion of:- (x/3+9y)^10 .

Find the middle terms in the expansion of:- (3- x^3/6)^7

Find the middle terms in the expansion of : (x/3+9y)^10 .

Find the middle term in the expansion of : (2x^2-1/(3x^2))^10 .

Find the middle terms in the expansion of : (x/y+y/x)^(2n+1) .

Find the middle term in the expansion of : (a/x+\ b x)^(12)

Show that coefficient of the middle term of (1+ x)^(2n) is equal to the sum of the coefficients of two middle terms of (1+x)^(2n-1) .