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Mathematics 20 Online
OpenStudy (king):

Its a log question so i shall give it in the reply......

OpenStudy (king):

\[\log_{3} (\log_{2} x) + \log_{1/3} (\log_{2} y)=1.\] Find x,y if given \[xy ^{2}=4\]

OpenStudy (anonymous):

alright what have you tried ?

OpenStudy (king):

um i took log base 1/3 as log base 3^-1 and that will be \[-\log_{3} \]

OpenStudy (anonymous):

log3(log2,x) + log1/3(log2,y) =1 log3(log2,x) - log3(log2,y) =1 log3(log2,x/log2,y) =1 log3(x/y) =1 x/y=3

OpenStudy (anonymous):

replace 1 with log base 3 of 3 then: \[\log_{3}(\log_{2}x) - \log_{3}(\log_{2}y) = \log_{3}3 \] then:\[\log_{2}x / \log_{2}y = 3\] \[\log_{y}x = 3 \] y^3 = x so y is 4^0.2 x = 4^0.6

OpenStudy (king):

can u please xplain how u got the 3rd equation?

OpenStudy (anonymous):

log a - log b = log(a/b)

OpenStudy (anonymous):

@King:From the first equation I got $\frac{x}{y} = 3$ can you do the rest ?

OpenStudy (king):

no log x base y

OpenStudy (king):

xplain

OpenStudy (anonymous):

oh ok. log a / log b = log a base b

OpenStudy (anonymous):

if they both have the same base. that is the rule

OpenStudy (king):

FFM what have u written?$\frac{x}{y} = 3$

OpenStudy (king):

oh ok

OpenStudy (king):

so ok how to find x,y

OpenStudy (anonymous):

read the rest. y^3 is x. and just plug that into your other equation

OpenStudy (anonymous):

yes king

OpenStudy (anonymous):

king its just substitution in the rest parts ..

OpenStudy (anonymous):

xy^2 becomes y^5 so y^5 =4 so y = 4^0.2 and x = y^3 = 4^0.6

OpenStudy (king):

ok...thnx guys can u solve 1 more question....shall i post it?

OpenStudy (anonymous):

go ahead

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