分式约分
问题描述：
分式约分
1.a的四次方-1/a²+2a+1
2.(x+y)² -10(x+y)+25/(x+y)²+25
答
1.=(a²)² -1²/(a+1)²
=(a²+1)(a+1)(a-1)/(a+1)²
=(a²+1)(a-1)/(a+1)
2.=x+y-5/(x+y+5)(x+y-5)