题干
观察下列等式：①a +
= 3 ；②a +
= 5 ；③a +
= 7 ；④a +
= 9 …；第n个等式____ ．
| 2 |
| a |
| 6 |
| a |
| a |
| a |
答案(点此获取答案解析）
a+
=2n+1
| n |
| ( |
| n |
| + |
| 1 |
| ) |
| a |
