(c^2+3c-2)^2 = (c^2+3c-2)(c^2+3c-2)
= c^4 + 3c^3 - 2c^2 + 3c^3 + 9c^2 - 6c - 2c^2 - 6c + 4
= c^4 + 6c^3 + 5c^2 - 12c + 4