8)
a) 2x²y+3x×(xy)-2x²×(3y)+3y×(3x²)=
= 2x²y+3x²y-6x²y+9x²y)=
= 8x²y
b) (2xy)×(3xy)+x²×(4y²)+(6x²y)(-2y)+2x²y²×2=
= 6x²y²+4x²y²-12x²y²+4x²y²=
=2x²y²
c)4ax×a²-2a³×2x+(-3a²x)(-3a)+2(-a³x)=
=4a³x-4a³x+9a³x-2a³x=
=7a³x
d)12a²×(-2b²)+2ab×(3ab)+4a²b×(-b)-3a×(-2ab²)=
=-24a²b²+6a²b²-4a²b²+6a²b²=
=-16a²b²
