题目内容
设等差数列{an}、{bn}的前n项和分别为Sn、Tn，若对任意自然数n都有
=
，则
+
的值为
______．
| Sn |
| Tn |
| 2n-3 |
| 4n-3 |
| a9 |
| b5+b7 |
| a3 |
| b8+b4 |
∵{an}，{bn}为等差数列，
∴
+
=
+
=
=
．
∵
=
=
=
=
，
∴
+
=
．
故答案为
∴
| a9 |
| b5+b7 |
| a3 |
| b8+b4 |
| a9 |
| 2b6 |
| a3 |
| 2b6 |
| a9+a3 |
| 2b6 |
| 2a6 |
| 2b6 |
∵
| S11 |
| T11 |
| a1+a11 |
| b1+b11 |
| 2a6 |
| 2b6 |
| 2×11-3 |
| 4×11-3 |
| 19 |
| 41 |
∴
| a9 |
| b5+b7 |
| a3 |
| b8+b4 |
| 19 |
| 41 |
故答案为
| 19 |
| 41 |
练习册系列答案
相关题目