$\"\"$

Definition of logarithmic functions $\"\"$ if and only if $\"\"$ .

Consider the base of the logarithmic function $\"\"$ .

Substitute $\"\"$ in $\"\"$ .

Therefore, the function is $\"\"$ .

Since $\"\"$ if and only if $\"\"$ .

$\"\"$ value is $\"\"$

$\"\"$ .

The base $\"\"$ is allowed to $\"\"$ only when $\"\"$ .

$\"\"$ is not true when the value of $\"\"$ .

$\"\"$

$\"\"$ value is $\"\"$ ,it is not true when the value of $\"\"$ .