Đáp án:
a,(x/3 - 1)^3=`(x/3)^3` -3.`(x/3)^2` +`3.1.3/x` -`1^3`
= `x^3/27` - `x^2` + x-1
b,( -y^2 + 3x)^3=`((-y)^2)^3`+`3.((-y)^2)^2.3x+`3.(-y)^2`.`(3x)^2`+`(3x)^3`
=`-y^6` + `9xy^4` - `27x^2y` + `27x^3`
c,(x/y - 2y/x)^3=`(x/y)^3` - `3.(x/y)^2` . `((2y)/x)` + `3.x/y` . `((2y)/x)^2` - `((2y)/x)^3`
= `x^3/y^3` - `(6x)/y` + `(12y)/x` - `(8y)^3/(x)^3`
d,(x+3)^3=`x^3` + `3.x^2.3` + `3.x` . `3^2` + `3^3`
=`x^3` + `9x^2` + `27x` + `27`
e,(1/2 - x)^3=`(1/2)^3` - `3.(1/2)^2.x` + ` 3.1/2` . `x^2` - `x^3`
=`1/8` - `12x` + `6x^2` - `x^3`
f,(2x - y^2)^3=`(2x)^3 - 3.`(2x)^2` . `(-y)^2` + 3.`2x` . `((-y)^2)^2)` - `((y^2)^3)`
=`8x^3` + `12x^2.y^2` - `6x.y^4` - `y^6`
