18. Factorise the expression with proper identity

$729x^3+y^3+z^3-27xyz$ \(=\) $\left(ix+i+i\right)\left(i{x}^i+y^i+z^i-ixy-iz-izx\right)$.

 

[Note: Insert answer as per the order of the identity and enter coefficient followed by the variable. Use answer boxes placed in superscript to enter the exponents.]