91Ó°ÊÓ

Find the sum of the first $20$terms of the geometric sequence$3,6,12,24,48,96,…$.

$a_n={\left(−1\right)}^n{n}^2.$Write the first five terms of the sequence whose general term is

Find the sum of the first $20$terms of the geometric sequence$6,18,54,162,486,1,458,…$

Find the sum.

$\underset{i=1}{\overset{15}{∑6}}{\left(2\right)}^i$

Find the sum:

$\underset{i=1}{\overset{10}{∑}}5{\left(2\right)}^i$

Find the sum of the infinite geometric series.

$48+24+12+6++3+\frac{3}{2}+...$

Find the sum of the infinite geometric series.

$64+16+4+1+\frac{1}{4}+\frac{1}{16}+...$

Write the repeating decimal $0.\overline{4}$as a fraction.

Write the repeating decimal $0.\overline{8}$ as a fraction.

What is the total effect on the economy of a government tax rebate of $\$1,000$ to each household in order to stimulate the economy if each household will spend$90\%$ of the rebate in goods and services?