Question

please explain the question

Answer 1

$(1 - x)(1 + x)(1 + {x}^{2} )(1 + {x}^{4} )(1 + {x}^{8} )$
Use,
$(1 + x)(1 - x) = 1 - {x}^{2}$
So, it becomes,
$(1 - {x}^{2} )(1 + {x}^{2} )(1 + {x}^{4} )(1 + {x}^{8} ) \\ (1 - {x}^{4} )(1 + {x}^{4} )(1 + {x}^{8} ) \\ (1 - {x}^{8} )(1 + {x}^{8} ) \\ 1 - {x}^{16}$