a) x4 + 2x3 + 2x2 + 2x + 1
= x4 + 2x3 + x2 + x2 + 2x + 1
= ( x4 + 2x3 + x2 ) + ( x2 + 2x + 1 )
= x2( x2 + 2x + 1 ) + ( x2 + 2x + 1 )
= ( x + 1 )2( x2 + 1 )
b) 4x8 + 1
= 4x8 + 4x4 + 1 - 4x4
= ( 2x4 + 1 )2 - ( 2x2 )2
= ( 2x4 - 2x2 + 1 )( 2x4 + 2x2 + 1 )