Question

(x-2)(x+2)(x²+4)-(x²+1)²+2(x+1)²

Answer 1

$(x-2)(x+2)=( x^{2} -4)$
$( x^{2} -4)( x^{2} +4)=( x^{4} -16)$
$( x^{2} +1)^{2}=x^{4} +1+2x^{2}$
$2(x+1) ^{2} =2(x^{2}+1+2x)$
$x^{4} -16-x^{4}-1-2x^{2}+2x^{2}+2+4x= -16-1+2+4x=-15+4x$