Regroup terms.

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, .

Rewrite as .

Reorder and .

Factor out of .

Factor out of .

Factor out of .

Rewrite as .

Factor out of .

Factor out of .

Factor out of .

Factor out of .

Remove unnecessary parentheses.

Factor out negative.

Multiply by .

Multiply by .

Factor a^2+4b-ab-4a