Question

若ab=2，a+b=5，（a+b）²=a²+2ab+b²，那么a²+b²+1=______．

Answer 1

因为ab=2，a+b=5，
则a²+b²+1
=（a+b）²-2ab+1
=5²-2×2+1
=25-4+1
=22．
故答案为：22，．