(5a-4b)^2-(5a-4b)(3a-2b)=(5a-4b)[5a-4b-(3a-2b)]=(5a-4b)(2a-2b)=10a^2-18ab+8b^2
(2x-1)(2x+1)(4x^2-1)=(4x^2-1)(4x^2-1)=(4x^2-1)^2