(c-1)(c-2)(c+2)(c+3)=

(c-1)(c-2)(c+2)(c+3)=
1)(c-1)(c-2)=(c^2-3c+2)
2)(c^2-3c+2)(c+2)=(c^3+2c^2-3c^2-6c+2c+4)=(c^3-c^2-4c+4)
3)(c^3-c^2-4c+4)(c+3)=c^4+3c^3-c^3-3c^2-4c^2-12c+4c+12=c^4+2c^3-7c^2-8c+12