3a²－5a＋2－6a²＋6a－3=3a²－6a²＋6a－5a＋2－3=(3－6)a²＋(6－5)a-1=-3a²＋a-1其中a＝－2分之1时,-3a²＋a-1=-3(-1/2)²＋(-1/2)-1=-3×(1/4)-1/2-1=-3/4-3/2=-3/4-6/4=-9/...