[poper]

ข้อ 2 ครับ
$x=\sqrt{2}-1$
$x+1=\sqrt{2}$
$x^2+2x+1=2$
$x^2+2x-1=0$
$x^{10}+2x^9-2x^8-2x^7+x^6+3x^2+6x+1$
$=x^8(x^2+2x-1)-x^6(x^2+2x-1)+3(x^2+2x-1)+4=4$