Rút gọn: (x+ 1)^2+ (x- 2)^2- 2x.(x+ 3)

1.Rút gọn
a,(x+1)^2+(x-2)^2-2x.(x+3)
b,(2x-3y)^2-(4x-6y+1)^2
c,(2x+y).(4x^2-2xy+y^2)-8x^3