1. ## Proof of logarithms

Hello,

I'm at a lost as to what to do here. I asked a teacher for help and he said these are based on certain kinds of logarithmic proof, but I've not been taught then.
If these really are based on certain logarithmic proofs, can someone fill me in on it so I can try the questions, please.

Prove the following:
1) 1/logxXYZ + 1/logyXYZ + 1/logzXYZ = 1 =>NUMERATOR IS 1.

2) if a, b and c are positive real integers, then (log $a$b)(log $b$c)= (log $a$c)

2. Originally Posted by Hellbent
Hello,

I'm at a lost as to what to do here. I asked a teacher for help and he said these are based on certain kinds of logarithmic proof, but I've not been taught then.
If these really are based on certain logarithmic proofs, can someone fill me in on it so I can try the questions, please.

Prove the following:
1) log $x$xyz + log $y$xyz + log $z$xyz = 1
If this means:

$\log_x(x.y.z)+\log_y(x.y.z)+\log_z(x.y.z)=1$

its not true, which can be seen by putting z=y=z=a, then the left hand side is:

$3\log_a(a^3)=9$

CB

3. Originally Posted by Hellbent
2) if a, b and c are positive real integers, then (log $a$b)(log $b$c)= (log $a$c)
To do this you need to know that:

$\log_x(y)=\frac{\log(y)}{\log(x)}$

where a $\log$ without subscript means a logarithm to any base.

CB

2.) (logaB)(logbC)= (logaB)(logaC)/(logaB)
= logaC

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# logbaÃ—logcbÃ—logac

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