(3x^2 - 4)(x + 3y) = 3x^3 + 9x^2y - 4x - 12y
(x + 3)(x^2 + 3x) = x^3 + 3x^2 + 3x^2 + 9x = x^3 + 6x^2 + 9x
(xy - 1)(x + 5) = x^2y + 5xy - x - 5
(3x + 5y)(2x - 7y) = 6x^2 - 21xy + 10xy - 35y^2 = 6x^2 - 11xy - 35y^2
-(x - 1)(x^2 - 2y) = -x^3 + 2xy + x^2 - 2y
(-x^2 + 2y)(x^2 + 2) = -x^4 - 2x^2 + 2x^2y + 4y
(x + 3y)(y - 3y + 2) = xy - 3x^2y + 2x + 3y^2 - 9y^2 + 6y = xy - 3x^2y - 6y^2 + 2x + 6y
(x + 2y)(x - 2y + 3) = x^2 - 2xy + 3x + 2xy - 4y^2 + 6y = x^2 + 3x - 4y^2 + 6y
(x^2 - xy + y^2)(x - y) = x^3 - x^2y - xy^2 + y^3 - x^2y + xy^2 - y^3 = x^3 - 2x^2y
(x^2 - xy + y^2)(x + y) = x^3 - x^2y + xy^2 + x^2y - xy^2 + y^3 = x^3 + y^3
(5x - 2y)(x^2 - xy + 1) = 5x^3 - 5x^2y + 5x - 2x^2y + 2xy^2 - 2y
(x^2y^2 - xy + y)(x + y) = x^3y^2 - x^2y^2 + xy^2 + x^2y^2 - xy^2 + y^2 = x^3y^2 + y^2
(x^2 - 2xy + y^2)(x - y) = x^3 - 2x^2y + xy^2 - x^2y + 2xy^2 - y^3 = x^3 - 3x^2y + 3xy^2 - y^3
-(x - y)(x^2 + xy - 1) = -x^3 - x^2y + x + x^2y + y^2 - y = -x^3 + x + y^2 - y
-(x^2 - 2y)(x + y) = -x^3 - x^2y + 2xy + 2y^2
(1/2x - 1)(2x - 3) = x^2 - 3/2x - 2x + 3 = x^2 - 7/2x + 3
(x - 1/2y)(x - 1/2y) = x^2 - 1/2xy - 1/2xy + 1/4y^2 = x^2 - xy + 1/4y^2
(x^2 - 2x + 3)(1/2x - 1) = 1/2x^3 - x^2 + 3/2x - x^2 + 2x - 3 = 1/2x^3 - 2x^2 + 7/2x - 3