x的4次+2x+1
因式分解
(x^4+x)+x+1
=x(x^3+1)+x+1
=x(x+1)(x^2-x+1)+(x+1)
=(x+1)(x^3-x^2+x+1)
X4+2x+1=x4-1+2x+2
=(x2+1)(x2-1)+2(x+1)
=(x2+1)(x+1)(x-1)+2(x+1)
=(x+1)((x2+1) (x-1)+2)
=(x+1)(x3- x2+x+1)