The coefficients of three consecutive terms in the expansion of `(1 + a)^n` are are in the ratio 1: 7: 42 Find n.

If the binomial coefficients of three consecutive terms in the expansion of (a+x)^n are in the ratio 1:7 :42 , then find n .

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

The coefficients of three consecutive terms of (1+x)^(n+5) are in the ratio 5:10:14. Then n= ___________.

If the coefficients of the r^(th) term and the (r + 1)^(th) term in the expansion of (1 + x)^(20) are in the ratio 1:2 , then r is equal to

If the coefficient of 4th term in the expansion of (a+b)^n is 56, then n is