:2(x-2y)^2-4(x-2y)+(x-2y)^2-3(x-2y)
=2(x-2y)^2+(x-2y)^2-4(x-2y)-3(x-2y)
=3(x-2y)^2-7(x-2y)
=(x-2y)(3(x-2y)-7)
代入=(-1-2*(1/2))(3(-1-2*(1/2))-7)
=26
:2(x-2y)^2-4(x-2y)+(x-2y)^2-3(x-2y)
=2(x-2y)^2+(x-2y)^2-4(x-2y)-3(x-2y)
=3(x-2y)^2-7(x-2y)
=(x-2y)(3(x-2y)-7)
代入=(-1-2*(1/2))(3(-1-2*(1/2))-7)
=26