Simplify: `(x+y-2z)^2-x^2-y^2-3z^2+4x y`

Simplify: (x+y-2z)^(2)-x^(2)-y^(2)-3z^(2)+4xy

Simplify : (-x-y-z)^2-(x+y-z)^2 .

Simplify : (x-y+2z)^2+(2x+y-z)^2 .

Simplify (x+y+z)^(3)-(x-y-z)^(2) .

Simplify: (x^2+y^2-z^2)^2-\ \ (x^2-y^2+z^2)^2

Simplify each of the following expressions: (x+y+z)^(2)+(x+(y)/(2)+(z)/(3))^(2)-((x)/(2)+(y)/(3)+(z)/(4))^(2)(x+y-2z)^(2)-x^(2)-y^(2)-3z^(2)+4xy-(x^(2)+x+1)^(2)-(x^(2)+x+1)^(2)

Simplify : (x+y+z)^2+(x+y/2+z/3)^2-(x/2+y/3+z/4)^2

Simplify (y-z)^2(z-y)+(z-x)^2(x-z)+(x-y)^2(y-x)+3(y-z)(z-x)(x-y)

Simplify: (x^(2)+y^(2)-z^(2))^(2)-(x^(2)-y^(2)+z^(2))^(2)