3ab-b^2+3a^2-ab = b (3a-b)+a(3a-b)=(3a-b)(b+a)
6y^2-3y+2ay-a=3y(2y-1) + a (2y-1)= (2y-1)(3y+a)
a^3-3a^2+a-3=a^2(a-3)+1(a-3)=(a-3)(a^2+1)
5a^3c-a^3+5bc-b=a^3(5c-1)+b(5c-1)=(5c-1)(a^3+b)
3ab-b^2+3a^2-ab = b (3a-b)+a(3a-b)=(3a-b)(b+a)
6y^2-3y+2ay-a=3y(2y-1) + a (2y-1)= (2y-1)(3y+a)
a^3-3a^2+a-3=a^2(a-3)+1(a-3)=(a-3)(a^2+1)
5a^3c-a^3+5bc-b=a^3(5c-1)+b(5c-1)=(5c-1)(a^3+b)