2ab^2·(-3ab^2)^2
=2ab^2·9a^2b^4
=18a^3b^6
2x(1-3x)-(2x-1)(4-3x)
=2x-6x^2-(-6x^2+11x-4)
=2x-6x^2+6x^2-11x+4
=-9x+4
(2x+y)^2=(2x-y)^2+8xy