Question

Factorise completely x^4 – 81​

Answer 1

Answer:

${x}^{4} - 81$

${ {x}^{2} }^{2} - { {3}^{2} }^{2}$

$( {x}^{2} + {3}^{2})( {x}^{2} - {3}^{2} )$

$( {x}^{2} + {3}^{2} )(x + 3)(x - 3)$