３次式の展開

問題次の式を展開せよ。$${\small (1)}~(3x-1)^3$$$${\small (2)}~(x+2y)^3$$$${\small (3)}~(3x+2)(9x^2-6x+4)$$$${\small (4)}~(2x-y)(4x^2+2xy+y^2)$$