$P = x^{95}+x^{94}+x^{93}+...+x^2+x+1 $
$= x^{94}.(x+1)+ x^{92}.(x+1)+ x^{90}.(x+1)+ ...+ x^{2}.(x+1)+ (x+1)$
$= (x+1)(x^{94}+ x^{92}+ x^{90}+ ... +x^{2}+ 1)$
$= (x+1)[x^{92}.(x^2+1)+ x^{88}.(x^2+1)+ x^{84}.(x^2+1)+ ...+ x^{4}.(x^2+1)+ (x^2+1)]$
$= (x+1)(x^2+1)(x^{92}+ x^{88}+ x^{84}+ ...+ x^{4}+ 1)$
$= (x+1)(x^2+1)[x^{88}. (x^4+1)+ x^{80}. (x^4+1)+ ...+ (x^4+1)]$
$= (x+1)(x^2+1)(x^4+1)(x^{88}+ x^{80}+ ...+ x^8+ 1)$
$= (x+1)(x^2+1)(x^4+1)[x^{80}.(x^8+ 1)+ x^{64}.(x^8+ 1) +...+ (x^8+ 1)]$
$= (x+1)(x^2+1)(x^4+1)(x^8+ 1)(x^{80}+ x^{64} +...+ x^16+ 1)$
$= (x+1)(x^2+1)(x^4+1)(x^8+ 1)[x^{64}.(x^{16}+ 1)+ x^32.(x^{16}+ 1)+ (x^{16}+ 1)]$
$= (x+1)(x^2+1)(x^4+1)(x^8+ 1)(x^{16}+ 1)(x^{64}+ x^{32}+1)$
b, Làm tương tự