Question 259983
<pre><font size = 4 color = "indigo"><b>
Color the first two terms black and the last two green

{{{1-x^2}}}{{{green(-y-xy)}}}

Factor the black part as the difference of two perfect squares:
Factor the green part by factoring out {{{green(-y)}}}

{{{(1-x)*(1+x))}}}{{{green(-y*(1+x)))}}}

Now I will recolor it:

{{{green((1-x))*red((1+x)))}}}{{{green(-y)*red((1+x)))}}}

Factor out the common red binomial factor {{{red((1+x)))}}}
and put the two green factors as a sum inside another parentheses:


{{{red((1+x))(green((1-x)-y))}}}

And you can remove the inner green parentheses:

{{{red((1+x))(green(1-x-y))}}}

And the final answer (without the colors) is

{{{(1+x)(1-x-y)}}}

Edwin</pre>