Please see below.
Work Step by Step
The exponents on $b$ in the expansion of $(a+b)^n$ increase by $1$ in each successive term. In the first term, the exponent on $b$ is $0$. The last term is $b^n$.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.