x◆y=x*y-x/2,x●y=x+y/2.0.1212的循环◆(7.5●4.8)=定义新运算x◆y=x*y-x/2,x●y=x+y/2.0.12 12的循环◆(7.5●4.8)=?

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简 x / y(x+y) - y / x(x+y) = x(x+y)(x-y)-y(y+x)(y-x)=(x-y)( )填空 y=x(x 填空：x-y/x+y=( )/x^2-y^2 （x-y)2•(y-x)³(x-y)=? (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x+x+x+x+y+y+y=56 (x-4y)(2x+y)= (x+y)(2x-3y)=? x+y>=2,x-y x+y>=2,x-y y'-2y=(e^x)-x y'+2y/x=x通解 dy/dx=(2x*x*x*y-y*y*y*y)/(x*x*x*x-2x*y*y*y) x+x+y+y+y=21 ,x+x+y+y+y+y+y=27 ,x ,y=?