(9x^2y-6xy^2-3xy)/6xy过程和结果后面的6xy没有带括号，是不是应该先除6再乘xy啊？？？？？？？

(x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， (9x^2y-6xy^2)/3xy 3xy(x^2y-xy^2+xy)-xy^2(2x^2-6xy+2x)过程 xy-2{xy-[3x^2y-(4xy^2+0.5xy)]+4x^2y}+6xy^2 （X-3xy+4xy-y）-[-2x-2（xy-3/2xy）-y]+6xy的过程 x^2-xy-6y^2+3xy+y+2 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y) 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) ①(9x²y-6xy²)÷3xy ②(3x²y-xy²+2分之1xy)÷(-2分之1xy) 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 ( )*3xy=6x^2y+2xy^2 [ 2x-6y][8-9xy]÷xy等于? -3x^2y+6xy^2-9xy=( )(x-2y+3) 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 已知xy/x+y=6,求3x-2xy+3y/-x+3xy-y的值. 已知(xy)/(x+y)=6求(3x-2xy+3y)/(-x+3xy-y)的值. 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) -9y^2+6xy-x^2