A=2xy+3x²y-1,В=3-2x²y
3A-2B
=6xy+9x²y-3-6+4x²y
=13x²y+6xy-9
=(13x²+6x)y-9
因为和y无关
所以
13x²+6x=0
x(13x+6)=0
x=0或x=-6/13