Question

(1+ a) (1- a) (1+a^2)​

Answer 1

$(1 + a)(1 - a)(1 + {a}^{2} )$

Using,

${a}^{2} - {b}^{2} = (a + b)(a - b)$

$= (1 - {a}^{2} )(1 + {a}^{2} ) \\ = 1 - {a}^{4}$