(a - b)(a + b) = a^2 - b^2 =>
(5y + 2x)(2x - 5y) = (2x + 5y)(2x - 5y) =
= (2x)^2 - (5y)^2 = 4x^2 - 25y^2
(a - b)(a + b) = a^2 - b^2 =>
(5y + 2x)(2x - 5y) = (2x + 5y)(2x - 5y) =
= (2x)^2 - (5y)^2 = 4x^2 - 25y^2