x-0.4x=36 2y-66=28 8x-6x=140 12x÷4=72 （解方程

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 x-0.4x=36 2y-66=28 8x-6x=140 12x÷4=72 （解方程 Y+X+X=36 Y-X-X=8 X=?Y=? 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 解这些方程组 (1) 7x-2y=96 5x-3y=45 (2) 4x+2y=50 2x+3y=47 (3) 4x+2y=66 7x-3y=70(4) 11x+9y=49 13x-3y=17 (5) 2y-x=1 13x-8y=59 (6) 18x+29y=307 16x+28y=284 （x+2y)(x-2y)-(2y-x)(-2x-y)其中x=8,y=-8 [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 12y(x-y)^2-8(x-y)^3=? 9y=3x-(x-1),4(x+y)-(2x+4)=8y [(2x-y)^2-y(y-4x)-8x]其中x=-1/2 已知x+y/x=11/8,求x-y/x+2y的值 y+x+2x=36 【x+_2y】[x-2y]-[2x-y][-2x-y]x=8 y=-8 [(2x+y)²-y(y+4x)-8x】/4x,其中x=-1,y=2005 急 y=2x+8/x求导