(2ax²-x²+3x+2)-(5x²-4x²+3x)
=2ax²-x²+3x+2-5x²+4x²-3x
=2ax²-2x²+2
因为与x无关,所以a=1
2a²-[3a²+(4a-5)+a]=2*1²-[3*1²+(4*1-5)+1]=2-(3-1+1)=-1
(2ax²-x²+3x+2)-(5x²-4x²+3x)
=2ax²-x²+3x+2-5x²+4x²-3x
=2ax²-2x²+2
因为与x无关,所以a=1
2a²-[3a²+(4a-5)+a]=2*1²-[3*1²+(4*1-5)+1]=2-(3-1+1)=-1