1.2x(2xy-z)(2xy+z)=2x(4x2y^2-z^2)
=8x^3y^2-2xz^2
2.a(a+c-b)3(a+c+b)=3a(a+c)^2-3ab^2
=3a^3+6a^2c+3ac^2-3ab^2