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Could someone explain to me why

$$x^{\log(n)} = n^{\log(x)}$$ in simple terms?

I tried to simply take the $log$ of both sides but it doesn't work out or simplify.

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    What do you get when taking the logarithms ?2017-01-28

2 Answers 2

10

Recall that logs and exponential functions are inverses, so they cancel, giving the following equality:

$$10^{\log(a)}=a$$

Using this, one can see that

$$x^{\log(n)}=(10^{\log(x)})^{\log(n)}=10^{\log(x)\log(n)}=(10^{\log(n)})^{\log(x)}=n^{\log(x)}$$

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    Also: It works the same with any base.2017-01-28
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    Thank you! That was very easy to understand.2017-01-28
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    @Zhinkk no problem :-)2017-01-28
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Remember the property $$\log(x^a) = a \log x \qquad a > 0$$ So taking $\log$ on both sides yields $$\log(x^{\log n}) = \log(n^{\log x}) \quad \Leftrightarrow\quad \log n \log x = \log x \log n$$ if $x,n \neq 1$, $x>0$. Now the equality should be more obvious.

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    I think the final equivalence to $1=1$ muddles rather than helps understanding here ...2017-01-28
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    @HenningMakholm Good point. Fixed it.2017-01-28