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Mathematics 7 Online
OpenStudy (anonymous):

Find x if 2log3x=6

OpenStudy (anonymous):

the 3 is a base

OpenStudy (anonymous):

x=3

OpenStudy (anonymous):

Did that help?

OpenStudy (anonymous):

how did you get that?

OpenStudy (anonymous):

Using the property of logarithm such that n log a = log a^n log3 x^2 = log3 (x+6) Since the logs on both the sides have same bases, they can be canceled out. So, x^2 = x + 6 x^2 - x - 6 =0 Now, factoring by regrouping: x^2 - 3x + 2x -6 = 0 x(x -3) + 2(x-3) = 0 (x-3) (x +2) = 0 x = 3 , x =-2 Since originally we had the term 2 log3 x..which shows that x should always be greater than 0 {Because log of negative number is not defined} Thus, x = 3

Nnesha (nnesha):

hmm log properties power property \[\huge\rm x \log ~y = b ---> log y^x = b \]

Nnesha (nnesha):

\[\huge\rm \color{red}{2} \log_3 x = 6\] apply power property

OpenStudy (anonymous):

so what's the answer?

OpenStudy (misty1212):

divide both sides by 2 and start with \[\log_3(x)=3\]

OpenStudy (misty1212):

then rewrite in equivalent exponential form as \[x=3^3\]

Nnesha (nnesha):

alright first we have to apply power rule \[\huge\rm \color{red}{2} \log_3 x = 6\] \[\huge\rm \log_3 x^\color{Red}{2} = 6\]

OpenStudy (misty1212):

or you can do it that way, but you don't need to use that property of the log dividing by 2 works also

Nnesha (nnesha):

now change log to exponential form |dw:1432346261784:dw|

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