2a^5-5a^4+2a^3-8a^2+3a+3
=2a^5-6a^4+2a^3+a^4-3a^3+a^2+3a^3-9a^2+3a+3
=2a^3(a^2-3a+1)+a^2(a^2-3a+1)+3a(a^2-3a+1)+3
=0+0+0+3
=3