A=2x²+3xy-2x-1
B=-x²+xy-1
3A+6B=3(2x²+3xy-2x-1)+6(-x²+xy-1)
=6x²+9xy-6x-3-6x²+6xy-6
=15xy-6x-9
=(15y-6)x-9
∵此代数式的值与x无关,
∴15y-6=0
y=2/5
A=2x²+3xy-2x-1
B=-x²+xy-1
3A+6B=3(2x²+3xy-2x-1)+6(-x²+xy-1)
=6x²+9xy-6x-3-6x²+6xy-6
=15xy-6x-9
=(15y-6)x-9
∵此代数式的值与x无关,
∴15y-6=0
y=2/5