(2x² + 5xy + 4y²) + (-xy - 6x² + 2y²) Try putting the second one under the first one, like this: (2x² + 5xy + 4y²) + (-xy - 6x² + 2y²) --------------------- No, that won't do. We'll have to swap the first two terms of the second one so like terms will be in line vertically. Now we can add them: ( 2x² + 5xy + 4y²) + (-6x² - xy + 2y²) --------------------- -4x² + 4xy + 6y² Edwin McCravy