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Mathematics 16 Online
OpenStudy (seratul):

Solve for t.

OpenStudy (seratul):

\[3^{t+8}=9^{2t}\]

OpenStudy (jdoe0001):

I assume you're covering logarithms?

OpenStudy (seratul):

Yep.

OpenStudy (sshayer):

\[3^{t+8}=9^{2t}=\left\{ \left( 3 \right)^2 \right\}^{2t}=3^{4t}\] t+8=4t t=?

OpenStudy (jdoe0001):

something to keep in mind log cancellation rules of \(\bf \large log_{\color{red}{ a}}{\color{red}{ a}}^x\implies x\qquad \qquad {\color{red}{ a}}^{log_{\color{red}{ a}}x}=x\)

OpenStudy (seratul):

I'm not sure how you got there sshayer. However, I converted it to t+8log3=2tlog9

OpenStudy (seratul):

Oh, I see how you got there sshayer. But do you know how to do it with the method where you add log to the equation?

OpenStudy (jdoe0001):

\(\large { 3^{t+8}=9^{2t}\implies 3^{t+8}=(3^2)^{2t}\implies 3^{t+8}=3^{4t} \\ \quad \\ \textit{using the log cancellation rule above} \\ \quad \\ log_{\color{red}{ 3}}\left( {\color{red}{ 3}}^{t+8} \right)=log_{\color{red}{ 3}}\left( {\color{red}{ 3}}^{4t} \right)\implies t+8=4t }\)

OpenStudy (sshayer):

solving by log \[3 ^{t+8}=9^{2t}=\left\{ \left( 3 \right) ^2\right\}^{2t}=3^{4t}\] take log of bothsides \[\left( t+8 \right)\log 3=4tlog3\] divide both sides log3 t+8=4t t=?

OpenStudy (sshayer):

\[\log~a^x=x~\log~a\]

OpenStudy (seratul):

I get it, thank you!

OpenStudy (sshayer):

yw

OpenStudy (jdoe0001):

you could also look at it, the longer way \(\bf log_{\color{red}{ 3}}\left( {\color{red}{ 3}}^{t+8} \right)=log_{\color{red}{ 3}}\left( {\color{red}{ 3}}^{4t} \right)\implies (t+8)(log_3(3))=(4t)(log_3(3)) \\ \quad \\ t+8=\cfrac{4t\cancel{(log_3(3))}}{\cancel{(log_3(3))}}\)

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