1.
For some n>10n > 10, let the coefficients of the 5th, 6th and 7th terms in the binomial expansion of (1+x)n+4(1 + x)^{n+4} be in A.P. Then the largest coefficient in the expansion of (1+x)n+4(1 + x)^{n+4} is:
Binomial Theorem and Its Simple Applications - Hard - Question