а) (2x - y)(x + y) = 2x^2 + 2xy - xy - y^2 = 2x^2 + xy - y^2

б) (a + b)(2a + 3b) = 2a^2 + 3ab + 2ab + 3b^2 = 2a^2 + 5ab + 3b^2

в) (3c + a)(2c - a) = 6c^2 - 3ac + 2ac - a^2 = 6c^2 - a^2

г) (6z - y)(2z - y) = 12z^2 - 6yz - 2yz + y^2 = 12z^2 - 8yz + y^2

д) (5x - c)(x - 5c) = 5x^2 - 25cx - cx + 5c^2 = 5x^2 - 26cx + 5c^2

е) (4m + 3n)(4m + 3n) = 16m^2 + 12mn + 12mn + 9n^2 = 16m^2 + 24mn + 9n^2

ж) (3y - 2v)(3y + 2v) = 9y^2 - 6vy + 6vy - 4v^2 = 9y^2 - 4v^2

з) (10x + 3z)(10x - 5z) = 100x^2 - 50xz + 30xz - 15z^2 = 100x^2 - 20xz - 15z^2