x+y=5,2x+y=8,x-2y=0,3x+2y=8

【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai 3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8 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 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 微分方程(1)(y'')^2+5y'-y+x=0;(2)y''+5y'+4y^2-8x=0;(3)(3x+2y)dx+( 6(x-y)-2(x+y)=14 3(x-y)+(x+y)=5 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 已知：3x=8y.求（1）x+y/y (2)2x+3y/x-2y y-3x=2,y-5x=4,y-7x=6,y-9x=8,y-11x=0方程组, （x+2y)(x-2y)-(2y-x)(-2x-y)其中x=8,y=-8