2A-3B
=2(3a²-2a+1)-3(5a²-3a+2)
=6a²-4a+2-15a²+9a-6
=-9a²+5a-4详细说明一下，整式我很不会其实不要说明了，2(3a²-2a+1)=2×3a²-2×2a+2×1 -3(5a²-3a+2)= -3×5a²+(-3)×(-3a)+(-3)×2 =6a²-4a+2-15a²+9a-6 =6a²-15a²-4a+9a+2-6