1) 5а - 3ab - 4a = a(5-3b-4)=a(1-3b)=a-3ab
2) 3a^2 b + b^4 - 4ba^2=b(3a^2+b^3-4a^2)=b(b^3-a^2)=b^4-a^2b
3) 7(a + b^2) - (a + b^2)=7a+7b^2-a-b^2=6a+6b^2
4) a^2 b^3 - (2ab)^2 + 3a^2 b^2=a^2b^3-4a^2b^2+3a^2b^2=a^2b^2(b-4+3)=a^2b^2(b-1)=a^2b^3-a^2b^2
5) 3(a - 2) + 3b + 6 = 3a-6+3b+6=3a+3b