①x²n+xn-1／9y²+¼n
= n(x²+x+1/4)-(1/3y)²
=n(x+1/2)²-(1/3y)²
这个是不是题目写错了
②x的十次方加上x的5次方减去2
=x^10+x^5-2
=(x^5+2)(x^5-1)