Question 258821
Whenever you have a difference of squares, it factors as follows.
{{{z^2-a^2=(z+a)(z-a)}}}
In your case,
{{{z^2=4x^2}}}
{{{z=2x}}}
{{{a^2=169}}}
{{{a=13}}}
{{{4x^2-169=(2x-13)(2x+13) }}}