a) ( 4x^2 + y^2 )( 2x + y )( 2x - y )
=(4x2+y2)(4x2-y2)
=16x4-y4
b) ( x + 1 )( x - 2 )( x^2 + 1)( x + 2 )( x - 1 )( x^2 + 4 )
=(x+1)(x-1)(x-2)(x+2)(x2+1)(x2+4)
=(x2-1)(x2-4)(x2+1)(x2+4)
=(x2-1)(x2+1)(x2-4)(x2+4)
=(x4-1)(x4-16)
=x8-17x4+16
a) \(\left(4x^2+y^2\right)\left(4x^2-y^2\right)\left(2x+y\right)\left(2x-y\right)\\ =\left(4x^2+y^2\right)\left(4x^2-y^2\right)\\ =16x^4-y^4\)
b) \(\left(x+1\right)\left(x-2\right)\left(x^2+1\right)\left(x+2\right)\left(x-1\right)\left(x^2+4\right)\\ =\left(x+1\right)\left(x-1\right)\left(x-2\right)\left(x^2+1\right)\left(x^2+4\right)\\ =\left(x^2-1\right)\left(x^2-4\right)\left(x^2+1\right)\left(x^2+4\right)\)
\(=\left(x^2-1\right)\left(x^2+1\right)\left(x^2-4\right)\left(x^2+4\right)\\ =\left(x^4-1\right)\left(x^4-16\right)\\ =x^8-17x+16\)