Simplify: (2a2−a+1)−(a2−a+1)(2a^2 - a + 1) - (a^2 - a + 1)(2a2−a+1)−(a2−a+1).
a2a^2a2
a2−2a+2a^2 - 2a + 2a2−2a+2
3a23a^23a2
000