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Mathematics 50 Online
OpenStudy (travis):

(logx)^(logx)=? pfft didn't do log for quite a while :P

OpenStudy (mertsj):

\[\log a ^{n}=nloga\]

OpenStudy (travis):

not logx^(logx)

myininaya (myininaya):

\[\text{ Let } y=(\log(x))^{\log(x)} \] Now do log( ) of both sides. \[\log(y)=\log[(\log(x))^{\log(x)}]\] Using properties of log we can rewrite as \[\log(y)=\log(x)\cdot \log(\log(x))\] Again we can use another property to rewrite this as Now I will write this as an exponential equation where the base is 10 assuming the base is 10 here. \[10^{\log(y)}=10^{\log(x)\cdot \log(\log(x))}\] \[y=10^{\log(x) \cdot \log(\log(x))}\] => \[(\log(x))^{\log(x)}=10^{\log(x) \cdot \log(\log(x))}\] Both still pretty ugly, but I honestly don't know what you want to show here.

OpenStudy (travis):

oh no, i have to proof its = x

myininaya (myininaya):

what is the base?

myininaya (myininaya):

i assumed it was 10

OpenStudy (travis):

10 i think question didnt write

OpenStudy (travis):

if it was another base im'm sure it wouldn't affect the answer

myininaya (myininaya):

The base would just be some other number if not 10

myininaya (myininaya):

\[(\log(x))^{\log(x)}=a^{\log(x) \cdot \log(\log(x))} \] if the base was a

OpenStudy (travis):

Solve the equation (logx)^logx=x

OpenStudy (travis):

thats how the question says

myininaya (myininaya):

Oh we are solving an equation

OpenStudy (travis):

log(logx)^logx=logx (logx)log(logx)=logx I cant cancel log on both sides right?

OpenStudy (bahrom7893):

yea u can

myininaya (myininaya):

\[\log(x)(\log(\log(x))-1)=0\]

myininaya (myininaya):

subtract log(x) on both sides

myininaya (myininaya):

both terms have log(x) in common

myininaya (myininaya):

you factor

OpenStudy (travis):

log(logx)=1 log(logx)=log10 logx=10 x=100 right?

myininaya (myininaya):

what about x=10 for log(x)=0 since log(10)=1

OpenStudy (travis):

oh wait log 100 isnt 10

OpenStudy (travis):

x= 10^10!

myininaya (myininaya):

\[x=10^{10}\]

myininaya (myininaya):

you have two solutions

OpenStudy (travis):

whats the other solution?

OpenStudy (travis):

i took out logx so logx=0 right

OpenStudy (travis):

or logx=1

myininaya (myininaya):

\[(\log(x))^{\log(x)}=x\] D log( ) on both sides \[\log(x) \cdot \log(\log(x))=\log(x)\] Now subtract log(x) on both sides \[\log(x) \cdot \log(\log(x))-\log(x)=0\] Now factor the expression on the left side \[\log(x)(\log(\log(x))-1)=0\] Now set both factors =0 So we have \[\log(x)=0 \text{ or } \log(\log(x))-1=0\] So we should solve both equations \[x=10 \text{ or } \log(\log(x))=1\] \[x=10 \text{ or } 10^{\log(\log(x))}=10^1\] \[x=10 \text{ or } \log(x)=10\] \[x=10 \text{ or } 10^{\log(x)}=10^{10}\] \[x=10 \text{ or } x=10^{10}\]

myininaya (myininaya):

But if we check both solutions....

OpenStudy (travis):

I divided the log away instead of subtracting it,now i get where i was wrong, thanks a lot that was very kind of you!

OpenStudy (travis):

cancel the 10 right?

OpenStudy (zarkon):

I think you ment to say x=1 though after checking one sees that is not a solution

OpenStudy (bahrom7893):

Travis you could have divided, you just made a mistake here: log(logx)=1 log(logx)=log10 logx=10 then x !=100

OpenStudy (bahrom7893):

10^log(x) = 10^10 x = 10^10

myininaya (myininaya):

oh yeah zarkon for some rason i solve log(x)=1

myininaya (myininaya):

reason*

OpenStudy (travis):

Yea I was too busy manipulating the log I didn't convert the log properly

myininaya (myininaya):

log(x)=0 x=1 for sure! :)

OpenStudy (travis):

yea so x =1 and x= 10^10

OpenStudy (zarkon):

x=1 is only a solution if you define \[0^0=1\]

myininaya (myininaya):

right which i don't define it that way

OpenStudy (travis):

but if you sub x = 10^10 it works too

myininaya (myininaya):

i would say that is the only solution

myininaya (myininaya):

because after checking x=1 we get 0^0 like zarkon said

OpenStudy (travis):

So reject that solution right

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