2ab-c)(2ab+c)= (2ab)^2 - c^2 = 4a^2b^2 - c^2(4+3xy)(4-3xy)= 4^2 - (3xy)^2 = 16 - 9x^2y^2(5a-3b)(5a+3b)= (5a)^2 - (3b)^2 = 25a^2 - 9b^2(5b+4a)(4a-5b)= (20a^2) - (25b^2) = 20a^2 - 25b^2(5x+6y)(6y-5x)= (30xy) - (25x^2) = 30xy - 25x^2(2p+7q)(7q-2p)= (14q) - (4p^2) = 14q - 4p^2
2ab-c)(2ab+c)= (2ab)^2 - c^2 = 4a^2b^2 - c^2
(4+3xy)(4-3xy)= 4^2 - (3xy)^2 = 16 - 9x^2y^2
(5a-3b)(5a+3b)= (5a)^2 - (3b)^2 = 25a^2 - 9b^2
(5b+4a)(4a-5b)= (20a^2) - (25b^2) = 20a^2 - 25b^2
(5x+6y)(6y-5x)= (30xy) - (25x^2) = 30xy - 25x^2
(2p+7q)(7q-2p)= (14q) - (4p^2) = 14q - 4p^2