化简:{(a+2/a²-2a)-(a-1/a²-4a+4)}÷(a-4/a)
先化简,再求值:(a-1)/(a+2)*(a²-4)/(a²-2a+1)÷1/(a²-1)
先化简,再求值:(a-2/a²+2a-a-1/a²+4a+4)÷a-4/a+2,其中a²+
1-a-b/a+2a/a²-b²/a²+4ab+4b² 求化简 ,
通分:a-1/(a+1)²-4,1-a/2-4a+2a²
a²-{-4ab+(ab-a²)}-2ab化简
化简a³-a²-4a
先化简,再求值:[(a²-1)/(a²-4)]•[(a+2)/(a²-2a+1
化简,a²-4a²-3a+6b
计算; [(-8)²-2×(-8)×1/4]÷(-27) 化简:5a²-[a²-[a&su
说明多项式说明(a-2)(a²+2a+4)-[3a(a+1)²-2a(a-1)²-(3a+
若2a²+3a+b=4,求{(a+b)(a-b)+(a-b)²+4a²(a+1)}/a的值
已知A=4a²-3a,B=2a²+a-1,求2A-3B.