Решите 100 б x^2y^2-1 25-36p^2c^2 4-c^2d^2 49x^2y^2-400

Решение
x^2y^2-1 = (xy - 1)(xy + 1)
25-36p^2c^2 = 5² - (6pc)² = (5 - 6pc)(5 + 6pc)
4-c^2d^2 = (2 - cd)(2 + cd)
49x^2y^2-400 = (7xy)² - 20² = (7xy - 20)(7xy + 20)