[tex]PQR=( {x}^{2} - yz)( {y}^{2} - {x}^{2} )( {z}^{2} - xy) = \\ = {x}^{2} {y}^{2} {z}^{2} - {x}^{3} {y}^{3} - {x}^{4} {z}^{2} + {x}^{5} y - {y}^{3} {z}^{3} + \\ + x {y}^{4} z + xy {z}^{3} - {x}^{2} {y}^{2} z[/tex]
I don't know if it was necessary to open the brackets, but I think you can write it like this:
[tex]PQR=( {x}^{2} - yz)( {y}^{2} - {x}^{2} )( {z}^{2} - xy) \\ [/tex]
