Factorise : a^3+ 2a^2 - a - 2 - Vidyadip

Question

Factorise $: a^3+ 2a^2 - a - 2$

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Answer

$a^3+ 2a^2 - a - 2$
$= a^2( a + 2 ) - 1( a + 2 )$
$= ( a^2 - 1 )( a + 2 )$
$= ( a + 1 )( a - 1 )( a + 2 ) [ \because a^2 - b^2 = ( a + b )( a - b )]$

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