x2+2(a+1)x+2a+1
=x²＋2ax＋2x＋2a＋1
=(x²＋2x＋1)＋(2ax＋2a)
=(x＋1)²＋2a(x＋1)
=(x＋1)(x＋2a＋1)


b2+c2+2ab+2ac+2bc
=(b²＋2bc＋c²)＋(2ab＋2ac)
=(b＋c)²＋2a(b＋c)
=(b＋c)(2a＋b＋c)

不懂的还可以问!满意请及时采纳! O(∩_∩)O