Regroup terms.

Factor out of .

Factor out of .

Rewrite as .

Factor out of .

Factor out of .

Rewrite as .

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

Rewrite the polynomial.

Factor using the perfect square trinomial rule , where and .

Since both terms are perfect squares, factor using the difference of squares formula, where and .

Apply the distributive property.

Multiply by .

Factor x^2-y^2-4y-4