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OpenStudy (anonymous):
\[3^{n+1}-3^{n-1}\]
OpenStudy (freckles):
well you can factor a 3^n out
OpenStudy (anonymous):
\[3^n~\times~3^1-3^n~\div~3^1\]
OpenStudy (anonymous):
Combining like terms
OpenStudy (freckles):
\[3^n(3-\frac{1}{3})\]
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OpenStudy (freckles):
now just find the difference of the fractions in the ( )
OpenStudy (anonymous):
\[3^n(\frac{ 8 }{ 3 })\]\[8(3^{n-1}) ?\]
OpenStudy (freckles):
those are both right
I don't know which of the ones you and your teacher find most simplified
OpenStudy (freckles):
what do you mean
OpenStudy (freckles):
we show our work I thought
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OpenStudy (freckles):
are you saying the final answer is suppose to be 8(3^(n-1)) ?
if so all you need is quotient rule
OpenStudy (freckles):
\[\frac{3^n}{3}8 =\frac{3^n}{3^1}8 =3^{n-1} 8\]
OpenStudy (anonymous):
Thnx @freckles
OpenStudy (freckles):
also here is another way:
\[3^{n+1}-3^{n-1} \\ 3^{n-1+2}-3^{n-1} \\ 3^23^{n-1}-3^{n-1} \\ 9(3^{n-1})-1(3^{n-1}) \text{you have like terms } \\ 8(3^{n-1})\]
OpenStudy (freckles):
either way @MARC_ \[8(3^{n-1})=8 \frac{3^n}{3^1} \text{ by quotient rule } \\ 8 \frac{3^n}{3} \text{ since } 3^1=3 \\ \frac{8}{3} 3^n \]
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