圆x^2+y^2+8x-6y+21=0与直线y=mx交于P,Q两点,O为坐标原点（1）求OP,OQ(2)求弦PQ中点M的坐标所满足的方程

圆x^2+y^2-8x+6y=0与x^2+y^2+4x-6y-12=0关于直线-----对称 两圆x^2+y^2-6x+16y=0与x^2+y^2+4x-8y-44=0的公切线条数 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) 设实数x,y满足方程:x^2+y^2-8x-6y+21=0 （1）求S=2x-y的最大值与最小值（2）求T=x^2+y^2-10x+2y+26的（2）求T=x^2+y^2-10x+2y+26的最大值与最小值. 已知圆x^2+y^2+x-6y+m=0与直线x+2y-3 2X-5Y+13=0 9X+6Y-8=0 求X与Y的值 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= X^2-Y^2+6X+10Y-30=0 X^2+Y^2-5X-8Y+21=0 X=?Y=? 圆C1：X*X+Y*Y+2Y-6Y-26=0与圆C2：X*X+Y*Y-4X+2y+4=0的公切线有多少条 圆x^2+y^2-4x+2y+4=0与圆x^2+y^2+2x-6y-26=0的位置关系 圆x^2+y^2+4x-6y+4=0与圆x^2+y^2+2x-4y-4=0的交点坐标 判定圆x^2+y^2-6x+4y+12=0与圆x^2+y^2-14x-12y+14=0是否相切? 判断圆X²+Y²-6X+4Y+12=0与圆X²+Y²-14X-2Y+14=0是否相切 2x-y=0与x+y=10 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 与圆x^2+y^2-4x=0外切,又与y轴相切的圆的圆心轨迹方程是A.y^2=8x B.y^2=8x(x>0)和y=0 C.y^2=8x(x>0) D.y^2=8x(x>0)和y=0(x