If the 6th, 7th and 8th terms in the expansion of `(x+a)^n` are respectivley 112, 7 and `1/4`, find x, a and n.

Find the 6th term in the expansion of (x+3)^9 .

Find the 4th term in the expansion of (x-2y)^12 .

Find a if the 17th and 18th terms in the expansion of (2+a)^50 are equal.

Find 5th term in the expansion of (2x^2-1/3x)^11 .

Find the 6th term in the expansion of (3x^2-1/3x)^8

If the 2nd, 3rd and 4th terms in the expansion of (x+a)^n are 240, 720 and 1080 respectively, find x ,\ a ,\ ndot

If the coefficients of 5th, 6th , and 7th terms in the expansion of (1+x)^n are in A.P., then n=

The coefficients of the (r-1)^(th) , r^(th) and (r+1)^(th) terms in the expansion of (x + 1)^n are in the ratio 1:3:5. Find n and r.

If the coefficient of the rth, (r+1)th and (r+2)th terms in the expansion of (1+x)^(n) are in A.P., prove that n^(2) - n(4r +1) + 4r^(2) - 2=0 .