Question 888545
<pre>
{{{3x^5y^2-21x^2y^7}}}

Look for a number.

3 is the largest common factor of 3 and 21, so we take out 3

Now look for letters.

x and y appear in both terms, and the LARGEST power we can take
out is the SMALLEST power that appears, which is {{{x^2}}} and {{{y^2}}}

So we take out the GCF, which is {{{3x^2y^5}}}

{{{3x^2y^2(x^3-7y^5)}}}

Edwin</pre>