(1) Simplify: `(x-1)(x-y-z)`

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

Simplify 3x(x-y) -y (x+y)

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

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

Simplify : : ( ( x+(1)/(y)) ^(a) ( x-(1)/(y))^(b))/((y+(1)/(x))^(a) (y-(1)/(x))^(b))

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

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

Simplify (3x^5y^3z^2)/(x^2yz^4)xxx^3y^3z

Simplify : x - y - {x-y - (x+y)-bar(x-y)}

When simplified (x^(-1)+y^(-1))^(-1) is equal to (a)\ x y (b) x+y (c) (x y)/(x+y) (d) (x+y)/(x y)