Tính: a) 1/2.x^2.2y^2.(2x + y).(2x - y); b) (12x - 5y).(2x - y + 1); c) (x - 1/2).(2x - 1).(x + 1)

Bài 1:
a, 1/2.x^2.2y^2.(2x+y).(2x-y)
b, (12x-5y). (2x-y+1)
c, (x-1/2). (2x-1). (x+1)
Bài 2: Khai triển
a,(2x+1/2) ^3
b, (3x-y) ^3
c,(1/3.x+1/2.y)
Bài 3:
a,(2x-1) . (4.x^2+2x+1)
b, (2+3x). (9.x^2-6x+4)
c,(x- y/2). (x+1/2.x.y+1/4.y^2)