Question

factorise the expression:a⁴-81​

Answer 1

(a²)²-(9)²

a=a² ,b=9²

(a+b) (a-b)

a²-3²

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(a²+3²) (a+3)(a-3)

Answer 2

Answer:

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Step-by-step explanation:

$\begin{gathered}a {}^{4} - 81 \\ = (a {}^{2}) {}^{2} - (9) {}^{2} \\ = (a {}^{2} + 9)(a {}^{2} - 9) \\ = (a {}^{2} + 9)(a) {}^{2} - (3) {}^{2} \\ \end{gathered} </p><p>$

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