化简:7a²b + (4a²b - 5a²b)- 2(2a²b-3ab²
化简 (a²+b²/a²-b²-a-b/a+b)÷2ab/(a-b)(a+b)&
先化简再求值 (a-2b)(a²+2ab+4b²)-a(a-5b)(a+3b),其中a=-1,b=2
化简a/a-b - b-a+b + 2ab/a²-b²
3ab+3b²/b(a²+2ab+b²) ×a²-b²/a-b ÷b/
(a+b/a-b)²×2a-2b/3a+3b÷ab/a²-b²
计算 (a²-2ab+b²-a+b)÷(a-b) (a+b)²÷(a-b)
计算:a/b(a-b)-b/a(a-b);(1/a+1/b)÷a²+2ab+b²/a+b.
化简 a²-2ab+b²/a²-b²+b/a+b
化简:a²-2ab+b²/a²-b²+b/a+b
计算:(a²-b²)/(a+b)+(a²-2ab+b²)/(a-b)
化简 (a+b)²+2a(a-1/2b)-3(a-b)(a+b)
(a-b)(a+b)²-(a+b)(a-b)²+2b(a²+b²)