Question

a4-20a2+64 factorise
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Answer 1

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• Factorise ${a}^{4} - 20 {a}^{2} + 64$

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${a}^{4} - 20{a}^{2} + 64$

$= {a}^{4} - 16 {a}^{2} - 4 {a}^{2} + 64$

$= {a}^{2} ( {a}^{2} - 16) - 4( {a}^{2} - 16)$

$= ({a}^{2} - 4)( {a}^{2} - 16)$

$= (a + 2)(a - 2)(a + 4)(a - 4)$

$\star\:\:\:\bf\large\underline\blue{Answer:-}$

• $(a + 2)(a - 2)(a + 4)(a - 4)$