已知x+y=6,xy=7,则x^2+y^2=_____,x^2+xy^2=____

已知X+y=6,xy=7 求x^2y+xy^2=已知X+y=6,xy=7 x^2y+xy^2 已知xy/x+y=3,则代数式2x-7xy+2y/-x+xy-y的值是多少? 已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y) 已知x+y=6,xy=-3,则x^2y+xy^2=? 已知x+y=6,xy=-3,则x∧y+xy∧2= 已知1/x=1/y=6,则3x-2xy+3y/3xy+x+y=?已知1/x+1/y=6,则3x-2xy+3y/3xy+x+y=? 已知x-y=8 xy=7,则3xy-2x+2y+4(y-x)²=? 已知x+y=7,xy=2,则x³y-2x²y²+xy³等于? 已知2/X-1/Y=3,则(X-2Y-XY)/(5XY+6Y-3X)=? 已知2/x-1/y=3,则(2y-x+4xy)/(3x-6y-5xy)=? 已知1/X+1/Y=6,则3X-2XY+3y/3XY+X+Y=多少 已知x+y=1,xy=-2,则x²y+xy²-2xy 已知x+y=6,xy=7,试求x*x+y*y,x*x-y*y的值 已知x.y满足X2-y2=2xy.则x-y/x+y=?x. 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y 已知x-xy=10,xy-y=2,则x-y=（ ）,-2xy+x+y=（ ）. 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x-xy=20,xy-y=-10,则x-y=( ),x+y-2xy=( ).