We have ,
\(=\text{x}^{4}+4\)
\(=\text{x}^{4}+4\text{x}^{2}+4-4\text{x}^{2}\)
\(=(\text{x}^{2}+2)^{2}-4\text{x}^{2}\)
\(=(\text{x}^{2}+2)^{2}-(2\text{x})^{2}\)
[\(\text{x}^{2}-\text{y}^{2}=(\text{x}-\text{y})(\text{x+y})]\)
\(=(\text{x}^{2}+2+2\text{x})(\text{x}^{2}+2-2\text{x})\)