Find the sum of `2x^2+y^2+xy,y^2-3z^2+yx, and z^2+x^2+zx+xyz-8`

Subtract 4x^(2) - z^(2) from the sum of 2x^(2) + 3y^(2) - 4z^(2) and x^(2) - 2y^(2) + z^(2)

From the sum of 2y^2+3yz, -y^2-yz-z^2 and yz+2z^2, subtract the sum of 3y^2-z^2 and -y^2+yz+z^2

Find the value of 4x^2+y^2+25 z^2+4x y-10 y z-20 z x when x=4,y=3 and z=2.

Find the value of 4x^2+y^2+25 z^2+4x y-10 y z-20 z x when x=4,\ y=3 and z=2

Find the product: (x+y+2z)(x^2+y^2+4z^2-x y-2y z-2z x)

Subtract the sum of (x^2-2y^2+xy) and (y^2+z^2+xyz) from the sum of (z^2-2zx-xyz) and (x^2+xy)

Find the product: (2x-y+3z)(4x^2+y^2+9z^2+2x y+3y z-6x z)

Find the product: (2x-y+3z)(4x^2+y^2+9z^2+2x y+3y z-6x z)

Find the product: (3x+2y+2z)\ \ (9x^2+4y^2+\ 4\ z^2-\ 6\ x y-4\ y z-6z x)

If |y z-x^2z x-y^2x y-z^2x z-y^2x y-z^2y z-x^2x y-z^2y z-x^2z x-y^2|=|r^2u^2u^2u^2r^2u^2u^2u^2r^2| , where r^2=x^2+y^2+z^2 & u^2= x y + y z+z x