49+14x+x²-y²
若x² +xy+y² =14,x² -xy+y²=28求x+y的值
若x²+xy+y²=14,x²-xy+y²=28,求x+y的值
(x²+4y²)²-16x²y² 因式分解
已知(x²+y²)(x²+y²-6)+9=0 ,求x²+y²
化简:1.2x²-y²+(2y²-3x²)-(2y²+x²)
化简再求值[(x²+y²)²-4x²y²]÷(x²-y&su
xy²/(x²y-y) × x²/(x²+x)=
xy²/(x²y) - y×x²/(x²+x)=
1-x²+2xy-y²
3x²-4xy+y²
(x+y)²-2(x²-y²)+(y-x)²
已知x²y²+x²+y²=10xy-16 求x,y