Rewrite as .

Let . Substitute for all occurrences of .

For a polynomial of the form , rewrite the middle term as a sum of two terms whose product is and whose sum is .

Factor out of .

Rewrite as plus

Apply the distributive property.

Factor out the greatest common factor from each group.

Group the first two terms and the last two terms.

Factor out the greatest common factor (GCF) from each group.

Factor the polynomial by factoring out the greatest common factor, .

Replace all occurrences of with .

Remove parentheses.

Remove parentheses.

Factor by Grouping 21x^2y^2+11xy-2