5x+11y-3xy怎么变成2(x-1)+8(y-1)=3(x-1)(y-1)?我的这个问题是有关于高中不等式的。原题是：已知x>1,y>1,且5x+11y-3xy=13,求x+y的最小值．答案的说明是由x>1，y>1，得x-1>0,y-1>0,又由5x+11y-3xy=13 2(x-1)+8(y-1)=3(x-1

2x^2-3xy-2y^2=0,怎么变成(2x+y)(x-2y)=0 2x^2-3xy-2y^2=0,怎么变成(2x+y)(x-2y)=0 5x+11y-3xy怎么变成2(x-1)+8(y-1)=3(x-1)(y-1)?我的这个问题是有关于高中不等式的。原题是：已知x>1,y>1,且5x+11y-3xy=13,求x+y的最小值．答案的说明是由x>1，y>1，得x-1>0,y-1>0,又由5x+11y-3xy=13 2(x-1)+8(y-1)=3(x-1 x的平方+xy-2y(x+y)x²-xy-2y²怎么变成(x+y)(x-2y) x^2+3xy+2y^2/x^2+2xy^2 怎样因式分解?答案是变成(x+2y)(x+y)/xy(x+2y),是怎么化的? 已知x+y=-1求：x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4的值.x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4 ①=(x+y)(x^3+4x^2y+xy+4xy^2+y^3) ②从第①步到第②步是怎么做的? x^2-xy-2y^2=0是怎么变成（x+y)(x-2y）=0求解, 已知xy/x+y=1/2,则代数式3x-5xy+3y/-x+3xy-y= 计算：(5-xy/x^3-x^2y)/(1-5/xy)^2*(y-x)^3 x²-y²+5x+3y+4（x+y-2xy)(x+y-z)+(xy-1）² 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= (-2xy+2x+5y)-(3xy+2y-2x)-(x+4y+xy)其中x-y=4xy=-1 5x^2y/-1/2xy*3xy^2 （x+y）(x-1)-xy-y^2 怎么因式分解? 5xy^2-{2x^y-[3xy^2-（xy^2-2x^2y）]/（-1/2xy）} 已知x^2+y^2=7,xy=-1,求代数式：5x^2-(3xy+4y^2)-(11xy-2y^2)-7x^2 已知x^2+y^2=7,xy=-1,求代数式:5x^2-3xy-4y^2-11xy+2y^2-7x^2 5x²-3xy²-2（2x²y-xy²）怎么写?