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avatar+9673 

\(\text{Simplify } \dfrac{\log\sqrt8+\log\sqrt{125}-\log\sqrt{27}}{\log2+\log\sqrt[3]{5}-\log\sqrt[3]{12}}\)

 Jul 19, 2016

Best Answer 

 #1
avatar+26393 
+10

 Simplify 

\(\dfrac{\log\sqrt8+\log\sqrt{125}-\log\sqrt{27}}{\log2+\log\sqrt[3]{5}-\log\sqrt[3]{12}}\)

 

\(\begin{array}{rcll} && \dfrac{\log\sqrt8+\log\sqrt{125}-\log\sqrt{27}}{\log2+\log\sqrt[3]{5}-\log\sqrt[3]{12}}\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} - \log{\sqrt[3]{3\cdot2^2}} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} - \log(\sqrt[3]{3}\cdot \sqrt[3]{2^2}) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\log\sqrt[3]{2^2} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\log(2^\frac23 ) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\frac23\cdot \log(2) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)-\frac23\cdot \log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac33\cdot\log(2)-\frac23\cdot \log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac13\cdot\log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac13\cdot\log(2) +\frac13\cdot\log(5) -\frac13\cdot\log(3) }\\\\ &=& \dfrac{ \frac32\cdot\log(2)+\frac32\cdot\log(5)-\frac32\cdot\log(3) }{\frac13\cdot\log(2) +\frac13\cdot\log(5) -\frac13\cdot\log(3) }\\\\ &=& \dfrac{\frac32}{\frac13} \left( \dfrac{ \log(2)+\log(5)-\log(3) }{\log(2) +\log(5) -\log(3) } \right) \\\\ &=& \dfrac{\frac32}{\frac13} \\\\ &=& \frac32 \cdot \frac31 \\\\ &=& \frac92 \\\\ &=& 4.5 \end{array}\)

 

laugh

 Jul 19, 2016
edited by heureka  Jul 19, 2016
 #1
avatar+26393 
+10
Best Answer

 Simplify 

\(\dfrac{\log\sqrt8+\log\sqrt{125}-\log\sqrt{27}}{\log2+\log\sqrt[3]{5}-\log\sqrt[3]{12}}\)

 

\(\begin{array}{rcll} && \dfrac{\log\sqrt8+\log\sqrt{125}-\log\sqrt{27}}{\log2+\log\sqrt[3]{5}-\log\sqrt[3]{12}}\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} - \log{\sqrt[3]{3\cdot2^2}} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} - \log(\sqrt[3]{3}\cdot \sqrt[3]{2^2}) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\log\sqrt[3]{2^2} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\log(2^\frac23 ) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)+\log{\sqrt[3]{5}} -\log\sqrt[3]{3} -\frac23\cdot \log(2) }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\log(2)-\frac23\cdot \log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac33\cdot\log(2)-\frac23\cdot \log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac13\cdot\log(2) +\log{\sqrt[3]{5}} -\log\sqrt[3]{3} }\\\\ &=& \dfrac{\log{\sqrt{2^3}}+\log{\sqrt{5^3}}-\log{\sqrt{3^3}} }{\frac13\cdot\log(2) +\frac13\cdot\log(5) -\frac13\cdot\log(3) }\\\\ &=& \dfrac{ \frac32\cdot\log(2)+\frac32\cdot\log(5)-\frac32\cdot\log(3) }{\frac13\cdot\log(2) +\frac13\cdot\log(5) -\frac13\cdot\log(3) }\\\\ &=& \dfrac{\frac32}{\frac13} \left( \dfrac{ \log(2)+\log(5)-\log(3) }{\log(2) +\log(5) -\log(3) } \right) \\\\ &=& \dfrac{\frac32}{\frac13} \\\\ &=& \frac32 \cdot \frac31 \\\\ &=& \frac92 \\\\ &=& 4.5 \end{array}\)

 

laugh

heureka Jul 19, 2016
edited by heureka  Jul 19, 2016
 #2
avatar+129852 
+5

[ log√8 + log √125  - log √27 ]  /  [ log 2 + log 3√5  -  log 3√12 ] =

 

[ log√8 + log √125  - log √27 ]  / log 3√8 + log 3√5 - log3√12 ] =

 

[ (1/2) log 8 + (1/2) log 125  -  (1/2)log 27 ] / [ (1/3) log 8  + (1/3) log 5 - (1/3) log12] =

 

[(1/2) log 23 + (1/2) log53 - (1/2) log 33 ] / [ (1/3) log 23 + (1/3) log 5 - (1/3) log12 ] =

 

 (3/2)[ log 2 + log 5 - log 3] / [ (1/3) [ log23 + log 5 - log 12] ] =

 

(3/2) [ log ( [2 * 5]  / 3 )  /  [ (1/3) [log [23 * 5 / 12 ]  )  =

 

(3/2) log (10/3) /  [(1/3) log (40/12) ]  =

 

(3/2) log (10/3) / [ (1/3) log (10/3) ] =

 

(3/2)  / (1/3)  = 

 

(3/2) * (3/1)  =

 

9/2  =

 

4.5

 

 

cool cool cool

 Jul 20, 2016

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