\(\begin{array}{l}
+)\;(5x - 2y)({x^2} - xy + 1)\\
= 5x.({x^2} - xy + 1) - 2y({x^2} - xy + 1)\\
= 5{x^3} - 5{x^2}y + 5x - 2{x^2}y + 2x{y^2} - 2\\
= 5{x^3} - 7{x^2}y + 5x + 2x{y^2} - 2\\
+)\;(x - 1)(x + 1)(x + 2)\\
= ({x^2} - 1)(x - 2)\\
= {x^2}(x - 2) - 1.(x - 2)\\
= {x^3} - 2{x^2} - x + 2
\end{array}\)