x+2y=9,xy=8,则x-2y=___

因式分解x^2-3xy-10y^2=__ 已知x-xy=20,xy-y=-10,则x-y=__,x+y=__. 若x,y为正整数,且x^2+y^2+4y-96=0,则xy=__. 如果X-Y=2,XY=80,那么X^2+Y^2=__ 若x-y=5,xy=6,则x^2y-xy^2=_,x^2+xy^2=__ 2 3 2 3 2 3 2x y+(-4x y)-(-3x y) 2 2 (3x+x-5)-(4-x+7x) 2 2 (8xy-3y)-5xy-2(3xy-2x)12 2 2 2 __ 5(3x y-xy)-(xy-3x y)其中x=2 y=-1算出来 诺{x+2y=6,2x+y=9则x+y=__ 已知x-xy=8,xy-y=-9,求x+y-2xy的值 已知1/x-1/y=3,则代数式2x-14xy-2y/x-2xy-y的值为__?各位知道的...已知1/x-1/y=3,则代数式2x-14xy-2y/x-2xy-y的值为__?各位知道的请支个招.感激不尽!2x-14xy-2y=-20xy?和x-2xy-y=-5xy?是怎样算出来的详细点喝, 填空 1、x²+6xy+__=(__+__)² 2、（ ）²+3/2xy+y²=（__+__）² 已知x+y=4,xy=2,则x的平方+y的平方__,x-y=__,x的四次方+y的四次方__ 已知|x+y+8|与|x-y+2|互为相反数,则x=__,y=__ x*x+xy=3,xy+y*y=2,则x*x+2xy+y*y=________? 已知xy/x+y=2,则代数式3x-5y+8y/-x+3xy-y的值 函数f(xy,x+y)=x^2+xy+y^2,则df(x,y)=? f(xy,x-y)=x^2+3xy+y^2,则f(x,y)=? 若x/y=2/7则7x²-3xy+2y²/2x²-3xy+7y²=x 2 7x²-3xy+2y²__= __ _____________ =y 7 2x²-3xy+7y² 若2x+y=0,则代数式4x³+2xy(x+y)+y³的值为__