List the first five terms of the sequence

$\{a_n\}=\{cos(n)\frac{n+1}{2n+3}\}$

Answer $q,$

Expand ${\displaystyle \underset{k=1}{\overset{4}{}}}(k^2+5)$ and find the sum $q,$

Answer $q,$

Express the finite series $31+27+23+$cdots$-1$ using summation notation

Towre$$t

Answer $q,$

Determine if the infinite geometric series converges or diverges. If it converges, find its sum

$2-1+\frac{1}{2}-\frac{1}{4}$cdots

Answer $q,$

Express the infinite series $81-27+9-3+$cdots using summation notation

Answer $q,$

${\displaystyle \underset{i=1}{\overset{n}{}}}(i)=1+2+3+$cdots$+n$ is an arithmetic series with a first term

of $1$ and a last term of $n.$ Use the formula $\frac{n}{2}(a_1+a_n)$ to find a formula for the sum ${\displaystyle \underset{i=1}{\overset{n}{}}}(i)$ in terms of $n.$