4x^2 + 4xy + y^2

1, 4x^2 + 4xy + y^2
2, -x^2 + 2xy - y^2
3, 1/9x^2 - 2/3x + 1
4, 25x^2 - 1
5, x^3 - 6x^2 + 12x + 7