x^8+x^6+3*x^4+1
=(x^4+1)^2+x^4(x^2+1)
=(x^4+1)^2+(x^4+1)(x^2+1)-(x^2+1)(设m=x^4+1,n=x^2+1)
=m^2+mn-n
=(m+n/2)^2-n-n^2/4
=(m+n/2)^2-n(4+n)/4(∵n>0,∴可推出下式）
={m+n/2-√[n(n+4)]/2}{m+n/2+√[n(n+4)]/2}
={x^4+1+(x^2+1)/2-√[(x^2+1)(x^2+5)]/2}{x^4+1+(x^2+1)/2+√[(x^2+1)(x^2+5)]/2}
={x^4+(x^2+3)/2-√[(x^2+1)(x^2+5)]/2}{x^4+(x^2+3)/2+√[(x^2+1)(x^2+5)]/2}
=(1/4){2x^4+x^2-√[(x^2+1)(x^2+5)]+3}{2x^4+x^2+√[(x^2+1)(x^2+5)]+3}
