1.圆x^2+y^2-2x-6y+9=0关于直线2x+y+5=0的对称方程是：A.:(x+7)^2+(y+1)^2=1 B.:(x+7)^2+(y+2)^2=1 C.:(x+6)^2+(y+2)^2=1 D.:(x+6)^2+(y-2)^2=1 2.一束光线从点A(-2,1)出发经x轴反射到圆C:(x-2)^2+(y-2)^2=1上,光线的最短路程为____

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 已知x^2-6xy+9y^2=0,求(x-y)/(x+y) (x+y)^2+6(x+y)+9 已知(x+y)(x+y-6)+9=0求2(x+y)的值 已知:(x+y)(x+y+6)+9=0 求2(x+y)的值 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) 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= x²-2x+y²+6y+10=0,求—9(x+y)²+(3x-2y)(2y+3x)的值 y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组,无 已知x^2+y^2+13-4x+6y=0,求(2x-y)^2-2(2x-y)(x+2y)+(x+2y)^2 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 三元一次方程解 1.{x+y-z=5 {3x+2y+z=2 {2x-2y+z=-31.{x+y-z=5 2.{9x-5y+x=-6 3.{x-y=3 4.{x+y=3 5.{4x-2y+z=7{3x+2y+z=2 {9x+y-2z=3 {x+z=7 {y+z=4 {2x-y-3z=28{2x-2y+z=-3 {-9x+3y-5z=0 {y-z=6 {z+x=5 {x+y-2z=13 1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 已知x,y为实数,根号3x+4 +y^2-6Y+9=0则x+y=? 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的值