\(\left(3x-1\right)^2-16\)
\(=\left(3x-1\right)^2-4^2\)
\(=\left(3x-1+4\right)\left(3x-1-4\right)\)
\(=\left(3x+3\right)\left(3x-5\right)\)
\(\left(3x-1\right)^2-16=\left(3x-1\right)^2-4^2\)
=\(\left(3x-1-4\right)\left(3x-1+4\right)\)
=\(\left(3x-5\right)\left(3x+3\right)\)