3a(a-b)-5b(a-b)

3a(a-b)-5b(a-b) (3a-6b)/(a+b) - (5a-6b)/(a-b) - (4a-5b)/(a+b) - (7a-8b)/(a-b (3a-6b/a+b）-(5a-6b/a-b)-(4a-5b/a+b)-(7a-8b/b-a) a+b>a-b, (a-b)(a b) a/b-b/a 因式分解（a-b)-3a+3b (a+b)(a-b)-2b(3a-5b) [（a+2b)(a-2b)-(2a-b)²+(3a-b)(3a-5b)]÷2a [a+b][a-b]+3a a-b>a,a+b （3a+2b)(6a-5b)(2b-3a)(5a+6b) 8a+2b+(5a - b) (5a-3b) -3 (a平方 - 2b)