Question

what is the 5th term

Answer 1

https://prnt.sc/s70f5w

Answer 2

For this you have to expand the polynomial

Answer 3

Use the fact that \[(a+b)^n = \binom n0a^n + \binom n1a^{n-1}b + \binom n2a^{n-2}b^2+\cdots + \binom nnb^n\]

So 5th term would be \(\displaystyle \binom n4a^{n-4}b^4\).