若X+6=Y-X-8=2X-3Y-1,则3X-Y=?

若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 若X+6=Y-X-8=2X-3Y-1,则3X-Y=? 若2X+3Y-1=Y-X-8=X+6则2X+Y= 若2x+3y-1=y-x-8=x+6，则2x-y=______． 若全集I={(x,y)|x,y∈R},集合M={(x,y)|(y-3)/(x-2)},N{(x,y)|y=x=1},则( 2x+3y-1=y-x-8=x+6,则x= 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y 若x+y=-1,则x^4+5x^3y+x^2y+8x^2y^2+xy^2+5xy^3+y^4=( ) 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值