factrorize $-a^3+a^2b+a^2c+ab^2-2abc+ac^2-b^3+b^2c+bc^2-c^3$ factrorize $-a^3+a^2b+a^2c+ab^2-2abc+ac^2-b^3+b^2c+bc^2-c^3$
or
$$ -(a^3 + b^3 + c^3) + (a^2 b + a b^2 + b^2 c + b c^2 + c^2 a + c a^2) - 2(abc)  $$
It is a so long polynomial I don't have any ideas for starting factoring what should I do?

$$   ( a +b - c)  ( b + c - a )  ( c + a - b)  $$
This is one factor short of Heron's formula,
$$  (a + b + c)  ( a +b - c)  ( b + c - a )  ( c + a - b) = 2 (b^2 c^2 + c^2 a^2 + a^2 b^2) - (a^4 + b^4 + c^4)  $$
