X —5\6=1\9 X+1\4=4\5 3x—X=0.9 2\7+X=3\4 y-2\5=3\4 4y-2y=1.2

若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-( 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 y=(x-1)(x-2)(x-3)(x-4)(x-5)(x-6)(x-7)(x-8)(x-9)(x-10)的导数在x=1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 3x+2y/4=2x+y/5=x-y+1/6 数学题……555{(3x+y)(3x-y)-(x-5y)(5x-y)-(x-2y)²÷(-4x),x=-2.y 3x-2y=1 4x-5y 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 9y=3x-(x-1),4(x+y)-(2x+4)=8y 3x+2=y 5X+4=Y 7X+6=Y 9X+8=y 11x=y要如何计算