(4a+5b)(5b-4a)-(-4a+5b)(-5b+4a)
=(4a+5b)(5b-4a)+(-4a+5b)(5b-4a)
=(4a+5b-4a+5b)(5b-4a)
=10b(5b-4a)还有一题= =麻烦了……已知a+b=2，ab=-二分之一求1:(a-b)^22:(a^2-1)(b^2-1)(a-b)^2=(a+b)^2-4ab=4+2=6(a^2-1)(b^2-1)=(ab)^2-(a^2+b^2)+1=1/4-(a+b)^2+2ab+1=1/4-4-1+1=-15/4