Question 937089
<pre>
{{{16m^2-n^2-16m+4}}}

Group the first third and fourth terms as a square trinomial:

{{{(16m^2-16m+4)-n^2}}}

Factor the trinomial {{{16m^2-16m+4=4(4m^2-4m+1)=4(2m-1)(2m-1)=4(2m-1)^2}}}

{{{4(2m-1)^2-n^2}}}

That's the difference of two squares:

[2(2m-1)-n][2(2m-1)+n]

[4m-2-n][4m-2+n]

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-3xy+6+2y-9x

Notice that 6 is 3 times 2 and -9 is 3 times -3.
So rearrange the terms like this, positive ones first and
negative ones last:

6+2y-9x-3xy

Factor the first two by taking out a 2.
Factor the last two by taking out -3x

2(3+y)-3x(3+y)

Take out common factor (3+y)

(3+y)(2-3x)

Edwin</pre>