Factorise: `27 x^3+y^3+z^3-9x y z`

Explanation

To factorise the expression \(27x^3 + y^3 + z^3 - 9xyz\), we can use the identity for the sum of cubes. The identity states:

\[ a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) \]

### Step-by-Step Solution:

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