Question

$(a {}^{2} −1)(a {}^{2} +1)$
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Answer 1

Step-by-step explanation:

apply (a-b) (a+b) = a²-b²

(a²)²-1²

= a⁴-1

Answer 2

Step-by-step explanation:

(a²-1)(a²+1)

= a²(a²+1) -1(a²+1)

= a⁴+a²- a²-1

= a⁴-1