Question 1132146
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<pre>
{{{x^2 + 2mn - m^2 - n^2}}} = {{{x^2}}} - {{{(m^2 - 2mn + n^2)}}} = {{{x^2}}} - {{{(m-n)^2}}} = (x+m-n)*(x-m+n).    <U>ANSWER</U>
</pre>

Solved.