Recent questions tagged arithmetic-series

The sum of the first $n$ terms in the sequence $\text{8, 88, 888, 8888,$\dots$}$ is __________.$\frac{81}{80}(10^n-1)+\frac{9}{8}n$$\frac{81}{80}(10^n-1)-\frac{9}{8}n$$\f...

Find the sum to $n$ terms of the series $10+84+734+….$$\frac{9(9^n+1)}{10}+1$$\frac{9(9^n-1)}{8}+1$$\frac{9(9^n-1)}{8}+n$$\frac{9(9^n-1)}{8}+n^2$