Question

Factorise y^3+y^2-y-1 ​

Answer 1

= y³ + y² – y – 1

= y² ( y + 1 ) – 1 ( y + 1 )

= ( y + 1 ) ( y² – 1 )

= ( y + 1 ) ( y + 1 ) ( y – 1 )

{ ( a² – b² = ( a + b ) ( a – b ) }