-1, -9x^2, 6x, -6x, 81x^4/4为什么?且看:9x²+1-1=(3x)^29x^2+1-9x^2=1^29x^2+1+6x=(3x+1)^29x^2+1-6x=(3x-1)^29x^2+1+81x^4/4=(9x^2/2+1)^2
+6x