Given,
\(\text{x}(\text{x}^3-\text{y}^{3})+3\text{x}\text{y}-(\text{x}-\text{y})\)
As \((\text{x}^{3}-\text{y}^{3})=(\text{x}-\text{y})(\text{x}^{2}+\text{x}\text{y}\,+\text{y}^{2})\)
\(\text{x}(\text{x}^{3}-\text{y}^{3})+3\text{xy}-(\text{x-y})\) = \(\text{x}[(\text{x-y})(\text{x}^{2}+\text{xy}\,+\text{y}^{2})\,+3\text{xy}-(\text{x-y})\)
Take \(\text{x}(\text{x-y})\) common to get,
\(\text{x}(\text{x-y})[(\text{x}^{2}+\text{x}+\text{y}^{2})+3\text{y}]\)