Question

二减a的四次方怎么算

Answer 1

a^2-a^4
=a^2(-a^2-1)
=a^2(a^2-1)
=-[a^2-1+1](a+1)(a-1)
=-[(a-1)(a+1)+1]（a-1）(a+1)
=-[(a-1)^2(a+1)^2+(a+1)(a-1)]
把（a+1）(a-1)提出来
=-{[(a+1)(a-1)](a+1)(a-1)+1}