那可以6×7=X÷Y 42=Y÷X 42=X分之Y X分之Y=42

那可以6×7=X÷Y 42=Y÷X 42=X分之Y X分之Y=42 [(2x-y)(2x+y)+y(y-6x)]÷2x=? 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 (x+y)(x-y)+(x-y)^2-(6x^2×y÷2y-2xy^2÷2y)其中x=-3,y=1/3 已知xy=-2,x-y=3,求（x+y)（x-y)-y^2+（x-y)^2-（6x^2y-2xy^2)÷2y {(x+2y)(x-2y)+[2(x-y)]²｝÷6x=? 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1 已知x²+y²+6x-8x+25=0,求（x/x²-y² - 1/x+y）÷y/y-x 那6X+5Y=31 2X+3Y=17 6x-2y+y-y=13-7? 计算：(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2 计算(x-y)^7÷(y-x)^6+9-x-y)^3÷(x+y)^2 {x=5y 3x+6y=42 x+y=6 10x+y≤42 {80/(x+y) +42/(x-y) =7 40/(x+y) +70/(x-y) =7 怎么解( ⊙ o ⊙ {80/(x+y) +42/(x-y) =7 40/(x+y) +70/(x-y) =7 快 急 {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 解方程组80/x+y + 42/x-y=7 40/x+y + 7/x-y=7非常感谢! 先化简,再求值:y(x-y)-x(x+y)/x²-y²÷x²+y²/x+y,其中x=2,y=-1