$\bf \qquad \qquad \textit{sum of a finite geometric sequence}
\\\\
S_n=\sum\limits_{i=1}^{n}\ a_1\cdot r^{i-1}\implies S_n=a_1\left( \cfrac{1-r^n}{1-r} \right)\quad 
\begin{cases}
n=n^{th}\ term\\
a_1=\textit{first term's value}\\
r=\textit{common ratio}
\end{cases}
\\\\\\
\sum\limits_{n=1}^{8}~-2(3)^{n-1}~~
\begin{cases}
n=8\\
a_1=-2\\
r=3
\end{cases}\implies S_8=-2\left( \cfrac{1-3^8}{1-3} \right)
\\\\\\
S_8=\underline{-2}\left( \cfrac{1-6561}{\underline{-2}} \right)\implies s_8=1-6561\implies S_8=-6560$

8 0

4 years ago

The commutative and associative properties work for which operations?

Norma-Jean [14]

Answer:

The associative and commutative properties can be used for addition and multiplication.

Step-by-step explanation:

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5 0

3 years ago

Write the equation of the line which contains the point (0,2) and has a slope of 3/4

DanielleElmas [232]

Answer:

y=3/4x+2

Step-by-step explanation:

4 0

3 years ago