x8+x+1=x8-x5+x5-x2+x2+x+1
=x5.(x3-1)+x2.(x3-1)+(x2+x+1)
=x5.(x-1)(x2+x+1)+x2.(x-1)(x2+x+1)+(x2+x+1)
=(x2+x+1)(x6-x5+x3-x2+1)
= x^5 - x^3 - x² - x^4 + x² + x + x^3 - x - 1
= x²( x^3 - x - 1 ) - x( x^3 - x - 1 ) + ( x^3 - x - 1 )
= ( x² - x + 1)( x^3 - x - 1 )
Sai òi Phương Nam Võ! Nek
x^5+x^4+1= (x^5+x^4+X^3)-(x^3+x^2+x)+(x^2+x+1)
=x^3(x^2+x+1)-x(x^2+x+1)+(x^2+x+1)
=(x^2+x+1)(x^3-x+1)
x8 + x + 1
= x8 - x2 + x2 + x + 1
= x2(x6-1) + x2+x+1
=x2(x3-1)(x3+1) + x2+ x + 1
=..................
.....
=x8-x7+x6-x7-x6-x5+x5-x4+x4-x3+x3-x2+x2+x+1
=x6(x2+x+1)-x5(x2+x+1)+x3(x2+x+1)-x2(x2+x+1)+(x2+x+1)
=(x2+x+1)(x6-x5+x3-x2+1)