a^2b^2 - 4a^3b^4 + ab + abc - 4a^2b^3c + c = a^2b^2 - 4a^3b^4 + ab + abc - 4a^2b^3c + c

= ab(a - 4a^2b^3 + c) + c(1 - 4a^2b^3)