9x^2-9y^2-x^4+y^4=0所表示的曲线是?答案是两条相交直线和一个圆

已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-2(x-y)=11 4(x+y)+3(x-y)=9 求x ,y 9x^2+4y^2-12x-8y+8=0 常微分方程的通解dy/dx=(x-y+1)/(x+y-3)y^4=2y^n+y=0y''+6y'+9y=e^(-3x)y''+y'-2y=4e^(2x) 已知x,y满足{3x-y=9 {x-3y=0 求x+2y+ 4y的平方/x-2y -4x的平方y/x的平方-4y的平方 9y=3x-(x-1),4(x+y)-(2x+4)=8y 根据3（x+y)-2(x-y)=11,4(x+y)+3(x-y)=9可得出x+y= ,x-y= y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组,无 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 x*x+2x+y*y-4y+5=0 x= y= 已知x,y为实数,根号3x+4 +y^2-6Y+9=0则x+y=? 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)}/x^2-9y^2的值 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=? 求由x²+y²=2,x²+y²=4x,y=x,y=0所围图形面积 求所有的整数对(x,y),使x^3-(x^2)*y+x*(y^2)-y^3=4(x^2)-4xy+4(y^2)+47