2a(x²+1）²-2ax²
=2a[(x²+1)²-x²]
=2a(x²+1+x)(x²+1-x)
2x²+2x+1/2
=1/2(4x²+4x+1)
=1/2(2x+1)²
如果本题有什么不明白可以追问,