已知：x²—y²=20,x+y=4,求x-y的值

已知：x²+y²+4x+6y+13=0 求：x²+y²的值 已知x²-y²=8,x-y=4,求x,y的值 已知：x²—y²=20,x+y=4,求x-y的值 已知x²+y²-4x+6y+13=0,求x²+2y/x²-3y²的值 x²+y²+4x-8y+20=0,求分式x²-y²/xy的值 已知实数满足x²+4y²=4x,求x²+y²的最值 已知x/y=3,求x²+2xy-3y²/x²-xy+y²的值 1.已知x²-10x+y²+4y+29=0,求x²+y²值. 已知x²+y²+8x+6y+25=0,求x-4y/x+y的值 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]/4y 已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y的值 已知x²+4x+y²-10y+29=0 求【x+2y】÷【x²-2y²】的值