Answer:
Explanation:
(3x + 7y)(3x - 7y) FOIL
9x² -49y² yes, this is difference of two squares
(2x - 7y)(2x - 7y) FOIL
4x² -14x -14x +49y²
4x² -28x + 49y² not difference of two squares
9x²(5x - 7) Distribute the 9x²
45x³ - 63x² not difference of two squares because one term is cubed
(6x - 4y)² Distribute the square term
36x² - 16y² yes, difference of two squares