a, \(=\left(x-3\right)^3\)
b, \(=-\left(\dfrac{x^3}{8}-\dfrac{3}{4}x^2+\dfrac{3}{2}x-1\right)=-\left(\dfrac{x}{2}-1\right)^3\)
c, \(=\left(x^2-\dfrac{1}{2}y\right)^3\)
`b, -x^3/8 + 3/4x^2 - 3/2 x + 1`
`= (-x/2 +1)^3`
`c, x^6 - 3/2x^4y + 3/4x^2y^2 - 1/8y^3`
`= (x^2-1/2y)^3`