(2/3x^4y^7-1/9x^2y^6)÷(-1/3xy^3)^2

(7x-2y)(3x-2y-1)-(4x+3y)(9x+6y)其中x=2y=1 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 81/8*(-x-y)^6*(x-y)^3*4/9(x+y)^4*(y-x)^2 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 试说明（4x*x-7X+6Y--1）-（-2x*x+3y*y+2Y+2X)+(-6X*X+9X-Y)的值于X无关. 帮忙解一些方程组(1)3x-2y=6 2x+3y=17 (2)5x+6y=15.2 3x-2y=-0.4(3)2(x+y)-3y=7 4(x-9)=3(y-2)(4)3(x+y)-4(x-y)=4 x+y/2+x-y/6=1 1、(-7x^y)(2x^y-3xy^3+xy) 2、((x-y)^6)/((y-x)^3)/(x-y) 把(x-y)看作一个整体,化简:(1)5(x-y)+2(x-y)-4(x-y);(2)3(x-y²-4(x-y)+7（x-y)-6(x-y) 解二元一次方程 {3(x+y)-4(x-y)=-9 x+y/2+x-y/6=1 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 计算:1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8x^7/(x^8+y^8) 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 1 x²y-3xy²2 2x(2x-y)+y(y-2x)3 -6x(m-2n)+12(2n-m)4 3(y-x)²-(x-y)³5 4a²-366 (x-2y)²-x²7 4x³y+4x²y²+xy³8 (x+y)²-2m(x+y)+m²9 x²-9x+1810 -8x²-10x-3 常微分方程的通解dy/dx=(x-y+1)/(x+y-3)y^4=2y^n+y=0y''+6y'+9y=e^(-3x)y''+y'-2y=4e^(2x) 很多很多数学题都是求x,y的1.2x-y=5 3x+4y=22.5x-y=110 9y-x=1103.8x+3y=7 5x-3y=6 4x+3y=6x-y=-25.4x-5y=1 2x-y=56.4x+3y=6 5x+6y=3 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 方程题4道1.4(x-y-1)=3(1-y)+3.5 (x/2)+(y/3)=2 2.2(x-y)/3-(x+y)/4=13/6 6(x+y)-4(2x-y)=16 3.3x-y+z=3 2x+y-3z=9 x+y+z=12 4.5x-4y+4z=13 2x+7y-3z=19 3x+2y-z=18 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7