Is $\displaystyle logx$ defined for $\displaystyle x = 0$?

No, because x > 0. Is this correct?

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Evaluate:

1)$\displaystyle log( \frac {1}{10^2} )$

My answer:

$\displaystyle -2 $?

2)$\displaystyle log_3 \sqrt3$

My answer:

$\displaystyle - \frac {1}{3}$ ?

3)$\displaystyle log_93$

My answer:

$\displaystyle \sqrt3$ ?

Can you please check to see if I did the questions correctly?

Thanks in advance.