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I was working on some math homework with a program called scientific notebook. I was check that I was writing something correctly.

The original equation is $(\log(x^4)+\log(x^5))/\log(8x)=7$

I then converted it to $\log(x^{(4+5)})=7\log(8x)$

I was expecting to get $\log((8x)^7)$ when I entered the $7\log(8x)$ into the program to evaluate. Can someone please explain this to me?

user93089
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wolfcall
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  • It sounds like your software interprets $\log$ and $\ln$ to mean the same thing. If by $\log$ you intend the meaning to be log base $10$ or anything other than $\ln$, then you may adjust your use of the software to get it to take the correct meaning of your input. – Jonas Meyer Oct 07 '13 at 15:23

1 Answers1

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In higher mathematics it is customary to take $\;\log=\ln=\log_e\;$ , and that's what most mathematicians mean when writing that.

Added: You had

$$\frac{\log x^4+\log x^5}{\log 8x}=7\iff \log x^9=7\log 8x=\log(8x)^7\implies$$

$$x^9=8^7x^7\implies x^2=8^7\ldots$$

DonAntonio
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