已知x/y=-2,求(x²-2xy-3y²)/(x²-6xy-7y²)
已知x/2=y/3(xy≠0),求x²-2xy-3y²/x²-6xy-7y²的值
已知xy²=-6,求xy(x^3y^7-3x^2y^5-11.5y)的值
已知x/y=2,求x²-xy+3y²/x²+xy+6y²的值
已知(x+2)²+│y-1│=0,求7x²y-3+2xy²-6x²y-2xy
已知x²+y²-8x+6y+25=0,求(x-y+4xy/x-y)(x+y-4xy/x+y)
已知x:y=3:2,求(x²+3xy)/(xy+2xy)
已知x/y=3,求(x²+2xy-3xy²)/(x²-xy+y²)
已知(x+3)+丨X-y+10丨=0 ,求5x²y-[2x²y-(3xy-xy²)-3x&
已知2x+y=0,求x-2y/x²+xy*(x²-y²)/x²-4xy+4y
已知x+y=4.x-y=6.求代数式xy(y²+y)-y²(xy+2x)-3xy的值
已知x、y的方程组3(x²+y²)-5xy=6,2(x²+y²)+xy=17,求
已知x/y=3,求x²+2xy-3y²/x²-xy+y²