2. Factor 4x^2y^2-(x^2+y^2-z^2)^2 as the product of four polynomials of degree 1.
4x^2y^2-(x^2+y^2-z^2)^2 =
[2xy + ( x^2 + y^2 - z^2) ] [ 2xy - (x^2 + y^2 - z^2)] =
[[ x^2 + 2xy + y^2] - z^2 ] [ 2xy - x^2 -y^2 + z^2 ] =
[ (x + y)^2 - z^2] (-1)[ x^2 - 2xy + y^2 - z^2] =
[ (x + y)^2 - z^2] (-1) [ ( x - y)^2 - z^2] =
[ (x + y)^2 - z^2] [ z^2 - (x - y)^2] =
[(x + y) + z ] [ (x + y - z] [ z + (x - y)] [ z - (x - y)] =
[ x + y + z ] [ x + y - z ] [ x - y + z] [ -x + y + z ]