giúp mk vs ạ , mk cảm ơn

`a) ( -3x^3 y^2 z ). ( -1/3 xy^2 )^2`

`= (-3)x^3 y^2 z . ( -1/3 )^2 . x^2 . ( y^2 )^2`

`= (-3)x^3 y^2 z . 1/9 x^2 y^4`

`= ( -3 . 1/9 ) .( x^3  . x^2 )( y^2 . y^4 ).z`

`= -1/3 x^5 y^6 z`

`b) 2x^2 y^2 . 1/4 xy^3 (-3xy)`

`= 2x^2 y^2 . 1/4 xy^3 (-3)xy`

`= [ 2. 1/4 . (-3) ] . ( x^2 .x.x) . ( y^2 . y^3 .y )`

`= -3/2 x^4 y^6 `

`@Hist`