7.2÷8+2y=5.

7.2÷8+2y=5. 已知:y=2x-5,求代数式[（x^2+y^2)-(x+y)^2-2y(x-y)]÷8y的值 [(X平方+ Y平方)-(X-Y)的平方+2Y(X-Y)]÷4y的值,其中2x-y=8快 急用啊 6y-(y+2分之y+2-y分之y)÷(y^3-4y-2y^2+8分之y) 怎么算 先化简,在求值：6y-(y+2分之y + 2-y分之y)除以y³-4y-2y²+8分之y,其中y= -2分之5先化简,在求值：6y-(y+2分之y + 2-y分之y)除以y³-4y-2y²+8分之y,其中y= -2分之5 已知x^2-8x+y^2-y+16又1/4=0,求[(x+y)(x-y)-(x+y)^2-2y(x-3y)]÷4y的值 已知x+4y-2x+8y+5=0,求x^4-y^4/2x+xy-y·2x-y/xy-y÷(x+y/y)的值.数学上交不不算请教下. y^2-6y-2÷2y-4= [2(x-y)^5-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2[2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2]÷2(x-y)^2 y的平方+2y+7=8,y=? y- 2y+1/2=9- 8-y/4 y-2y+1/2=9-8-y/4 y-2[y-4(y-1)]-8=0 12y(x-y)^2-8(x-y)^3=? 2x-y=2,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 解二元一次方程组,1.x-y=3 2x-3y=4 2.2x-y=4 3x-4y=8 3.x-3y=5 3x-4y=8还没完呢.4.3x-2y=5 3x+3y=10 5.-2x+3y=4 -2x+4y=6 6.3x-5y=4 6x+5y=14 7.2x-3y=5 4x-3y=7 8.x+3y=4 2x+5y=5 9.x+3y=4 -2x+5y=5 10.2x+5y=7 3x-4y=8 2y+8y-1=0