(3x2 - x2) + (4x3) + (2 - 7)
\((3x^2 - x^2) + (4x^3) + (2 - 7)\\ =3x^2 - x^2 + 4x^3 + 2 - 7\\ =2x^2 + 4x^3 -5\\ = 4x^3+2x^2 -5\\ \)
