$\left(2a+b-3c+4\right)^2\:\:\left(6a+2b-3c\right)\:\:\left(a-b\right)$

$24a^{4}+8a^{3}b-84a^{3}c-18a^2b^2-12b^{3}a+57ab^2c-2b^{4}+15b^{3}c+6a^2\left(-3c\right)^2-4ab\left(-3c\right)^2-3ac\left(-3c\right)^2-2b^2\left(-3c\right)^2+3cb\left(-3c\right)^2-192a^2c+120acb+72ac^2+72cb^2-72c^2b+96a^2-64ab-48ac-32b^2+48cb+12a^2bc+36a^2c^2-18ac^2b+96a^{3}-16a^2b-64ab^2-18c^2b^2-16b^{3}$