Question 824042
A = (a^2 − 3a +1)^2 − (1− a)(−2a +1)(1− 3a)
A = (a^4-6a^3+11a^2-6a+1)-(-6a^3+11a^2-6a+1)
A = a^4

Just separate it into two sections and multiply out using the box method ( http://www.purplemath.com/modules/factquad3.htm ). Once multiplied out subtract like terms.