(2x-y)(x+y) = 2x^2 - xy + 2xy - y^2 = 2x^2 + xy - y^2(a+b)(2a+3b) = 2a^2 + 3ab + 2ab + 3b^2 = 2a^2 + 5ab + 3b^2(3c+a)(2c-a) = 6c^2 - 3ac + 2ac - a^2 = 6c^2 - a^2(6z-y)(2z-y) = 12z^2 - 6zy - 2zy + y^2 = 12z^2 - 8zy + y^2
(2x-y)(x+y) = 2x^2 - xy + 2xy - y^2 = 2x^2 + xy - y^2
(a+b)(2a+3b) = 2a^2 + 3ab + 2ab + 3b^2 = 2a^2 + 5ab + 3b^2
(3c+a)(2c-a) = 6c^2 - 3ac + 2ac - a^2 = 6c^2 - a^2
(6z-y)(2z-y) = 12z^2 - 6zy - 2zy + y^2 = 12z^2 - 8zy + y^2