Упростить. (a+1)(a-1)(a²+1)-(9+a²)

Question

Упростить.
(a+1)(a-1)(a²+1)-(9+a²)

Answer 1

(а+1)(а-1)(а²+1) - (9+а²) = (а²-1)(а²+1)-(9+а²) = а⁴-1-9-а²=а⁴-а²-10