(x^2+1)^3=x^6+3x^4+3x^2+1
(x^2+1)^3-(x^6+2x^4+2x^2+1)
=x^4+x^2
=x^2(x^2+1)
≥0
∴ (1)x=0时,(x^2+1)^3=x^6+2x^4+2x^2+1
(2)x≠0时,(x^2+1)^3>x^6+2x^4+2x^2+1
(x^2+1)^3=x^6+3x^4+3x^2+1
(x^2+1)^3-(x^6+2x^4+2x^2+1)
=x^4+x^2
=x^2(x^2+1)
≥0
∴ (1)x=0时,(x^2+1)^3=x^6+2x^4+2x^2+1
(2)x≠0时,(x^2+1)^3>x^6+2x^4+2x^2+1