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Write $2\log_4(x-1)$ as a single logarithm:

$\log_4(x^2-2x-1)$

$\log_4(x^2+2x+1)$

$\log_4\left(\left(x-1\right)^2\right)$

$\log_4(2(x-1))$

It cannot be written as a single logarithm

None of these