`1,(2x-1/3)³`
`=(2x)³- 3 . (2x)².1/3 + 3 . 2x . 1/3²-1/3³`
`=8 - 4x² + 2/9x-1/27`
`2,(1/3x + 1)³`
`=(1/3x)³ + 3.(1/3x)².1+ 3.(1/3x).1²+1³`
`=1/27+1/9x²+x+1`
`=28/7+1/9x²+x`
`3,16 - 8x + x^2`
`=4²-2.4.x+x²`
`=(4-x)²`
`4,x³ - 6x + 12x - 8`
`=x³-3.x².2+3.x.2²-2³`
`=(x-2)³`
Xin hay nhất !