In the expansion of (x+y)n , the coefficients of 4th and 13th terms are equal, Then the value of n is :
15
12
9
21
If the coefficients of rth term and (r+4)th term are equal in the expansion of (1+x)20, then the value of r will be
If the coefficients of 7th and 13th terms in the expansion of (1 + x)n are equal, then n is equal to