Question

factorise this: a^4 - 81 ​

Answer 1

ANSWER✔

$\sf\implies a^4-81=0$

$\sf\therefore property\:used\:=a^2-b^2=(a+b)(a-b)$

$\sf\implies (a^2+9)(a^2-9)$

$\sf\implies (a^2+9)(a^2-3^2)$

$\sf\implies (a^2+9)(a+3)(a-3)$

$\sf\implies 3,-3,$

________________

Answer 2

$\huge\underline{\red{⛥❃꧁αղsw៩Ʀ꧂⛥❃}}$

$\sf\implies a^4-81=0$

$\sf\therefore property\:used\:=a^2-b^2=(a+b)(a-b)$

$\sf\implies (a^2+9)(a^2-9)$

$\sf\implies (a^2+9)(a^2-3^2)$

$\sf\implies (a^2+9)(a+3)(a-3)$

$\sf\implies 3,-3,$