证明下列极限不存在(1) Lim x+y/x-y (2)lim x²y²/ x²y&sup
证明下列极限不存在(1) Lim x+y/x-y (2)lim x²y²/ x²y&sup
1-x²+2xy-y²
分式的约分与通分问题约分 (x²+xy)/(x+y)² x²-y²/(x&sup
(x+y)²-2(x²-y²)+(y-x)²
计算:(1).(-2xy²)*(3x²y)²
化简:1.2x²-y²+(2y²-3x²)-(2y²+x²)
1、已知xy满足(x+1)²+1y+21=0试求-2xy·5x²y+(0.5x²y&sup
1、证明x³+y³≥x²y+y²x
因式分解:4x²-y²-2y-1
x²-4y²/x²+2xy+y²÷x+2y/2x²+2xy
x³y³-x²y²-xy+1
x²-4y² x+2y