1.(2x+y+1)(2x+y-1)2.(x-2)(x+2)-(x+1)(x-3)3.(ab+1)平方-（ab-1)平方4.（2x-y)平方-4（x-y)(x+2y)

1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 1.(x-y)(x+y)+(x-y)+(x+y)2.x(x+2)-(x+1)(x-1),其中x=-二分之一请写清步骤,结果. [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 计算：1.（x-1)^2+2(1-x) 2.(x-y)/(x+3y)÷(x^2-y^2)/(x^2+6xy+9y^2)-2y/(x+y）1.（x-1)^2+2(1-x)2.(x-y)/(x+3y)÷(x^2-y^2)/(x^2+6xy+9y^2)-2y/(x+y） 先化简,再求值：y(x+y)+(x+y)(x-y)-x^2,其中x=-2,y=-1/2. {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 先化简,再求值:y(x+y)+(x+y)(x-y)-x²,其中x=-2,y=1/2. 1.计算(a^2+a+1)(a^2-a+1) 2.计算(x-y)(x+y)+(3x-2y)(2x+y)-x(6x-y) 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 因式分解1.(x^2-y+1)(x^2+1)+x^2y+y-x^2 2.(x+5y)^2+(2x+10y)(3x-y)+(y-3x)^2 1.y=x^5+5^x+x^x+lgx 2.y=xe^x^2求y'' 3.已知y=e^f(x),则y''= 4.已知y=(1+x)^x,求导数y' (x-y)(2x-y-1) (x/x+y-x/y-x-2xy/x.x-y.y)/(1/x-1/y) 分式化简 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 1.(x^3-x^2-4x+1)/(x^2-3x+2)-(x^3-2x^2-9x+21)/（x^2-5x+6）+（x^2-3x+8）/（x^2-4x+3）2.{(x^2)/（x-y)}*{y/(x+y)}-{(x^4y)/(x^4-y^4)}÷{（x^2/x^2+y^2）^2} 1.(2/x+y) - (1/x-y) = 2.当x=1984 y=1916时 :(x^4-y^4/x^2-2xy+y^2) × (y - x/x^2+y^2) = 先化简再求值:(x+y)(x-y)+(x^2-2xy+y^2)-(x^2y)^3÷(x^2y)^2,其中x=1,y=2. 解下列方程组1.（x-y+2)(x+y)=0 x²+y²=8 2.（x+y)(x+y-1)=0 (x-y)(x-y-1)=0