Solution :
[tex]x {}^{8} - y {}^{8} = (x {}^{4} ) {}^{2} - (y {}^{4} ) {}^{2} [/tex]
[tex] = (x {}^{4} + y {}^{4} )(x {}^{4} - y {}^{4} )[/tex]
[tex] = (x {}^{4} + y {}^{4} )[(x {}^{2} ) {}^{2} - (y {}^{2} )] [/tex]
[tex] = (x {}^{4} + y {}^{4} )(x {}^{2} + y {}^{2} )(x {}^{2} - y {}^{2} )[/tex]
[tex] = (x {}^{4} + y {}^{4} )(x {}^{2} + y {}^{2} )(x + y)(x - y)[/tex]
