圆x^2+y^2-4x-6y+9=0的半径是

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.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 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 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^2+4y^2-6x+4y+10=0,求x^4-y^4/(x+2y)(x-2y)*x+2y/xy^2+y^3除以（x^2+y^2/y)^2的值 x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 化简求值：已知x、y满足：x^2+y^2-4x+6y+13=0 求代数式 的值.(3x+y)^2-3(3x-y)(x+y)-(x-3y)(x+3y)急用！ x^2+y^2+6x-4y+13=0求x,y,x^2-y^2的值 已知：4x^2+y^2-4x-6y+10=0,求y/x-x/y的值 已知x²+y²+6x-2y+10=0,求8y分之9x²-y² + 4分之y-3x的值 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 x^2+y^2+4x-6y+13=0,求x^y的值 x^2+y^2-4x+6y+13=0,x,y的值 x^2-4x+y^2-6y+13=0求x,y的值 已知4x²+y²-4x-6y+10=0求（2/3x（√9x）+(y²√x/y³)×(x²√1/x×5x√y/x)的值 已知4x²+y²-4x-6y+10=0求（2/3x（√9x）+(y²√x/y³)-(x²√1/x-5x√y/x)的值