过圆x*x+y*y-2x+4y+1=0外一点p(0-4)向圆引切线,求切线方程

过圆x*x+y*y-2x+4y+1=0外一点p(0-4)向圆引切线,求切线方程 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 求过两圆C1:x^2+y^2+4x+y+1=0及C2:x^2+y^2+2x+2y+1=0的交点,且面积最小的圆的方程用x^2+y^2+4x+y+1+b（x^2+y^2+2x+2y+1）=0的方法 x*x+2x+y*y-4y+5=0 x= y= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 {4x-3y-10=0 3x-2y=0,{3x-4(x-y)=2 2x-3y=1,{2(x+y)-(x-y)=3 (x+y)-2(x-y)=1 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 {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? x+y+2(-x-y+1)=3(1-y-x)-4-(y+x-1),x+y=? 求过已知圆x^2+y^2-4x+2y=0,x^2+y^2-2y-4=0的交点,且圆心在2x+4y=1上的圆的方程 设x大于1,y大于0,x^y+x^-y=2根号二,x^y-x^-y等于? 求过直线2x+y+4=0和圆x^2+y^2+2x-4y+1=0的焦点和原点 如果|x-y+1|+y^2-4y+4=0,求出x,y的值 x,y>0,且x+2y=1,u=(x+1/x)(y+1/(4y)最小值是: (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知:【(x²+y²)-(x-y)²+2y(x-y)】/4y=1,求4x/4x²-y²-1/2x+y