(2x-3)(4x^2+6xy+9)就是这个等于多少

(2x-3)(4x^2+6xy+9)就是这个等于多少 -3(2x^2-xy)+4(x^2+xy-6) 4(x²+xy-6)-3(2x²-xy) -3(2x²-xy)+4(x²+xy-6) (x-2xy)*(-xy+2y*y)-(3x*x-2xy)(x-9xy+6y*y)答案应为-2x-x*x-3x， 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 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 (1)32x^3-2x (2)-14xy-x^2-49y^2(3)x^3-xy^2 (4)x^3-6x^2+9x 5x^3y*(-3y)^2+(-6xy)^2*(-xy)+xy^3*(-4x^2) (9x^2y-6xy^2)/3xy 3xy(x^2y-xy^2+xy)-xy^2(2x^2-6xy+2x)过程 （-3x^y+2xy)-( )=4x^+xy 4x的平方+3xy-x的平方-3xy+9,其中x=-2 -3(2x-xy)-4(-6+xy+x.其中x=1,y=-1 因式分解3x^2-6xy+x 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 化简：x-y/x+3y÷x^-y^2/x^2+6xy+9y^2-(xy/x+y)