题目：
在物理电学中，如图所示的电路总电阻R与R1与R2的关系：| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
答案
解：| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
变形得：
| 1 |
| R |
| R1+R2 |
| R1R2 |
则R=
| R1R2 |
| R1+R2 |
解：
| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
变形得：
| 1 |
| R |
| R1+R2 |
| R1R2 |
则R=
| R1R2 |
| R1+R2 |
在物理电学中，如图所示的电路总电阻R与R1与R2的关系：| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
| 1 |
| R |
| R1+R2 |
| R1R2 |
| R1R2 |
| R1+R2 |
| 1 |
| R |
| 1 |
| R1 |
| 1 |
| R2 |
| 1 |
| R |
| R1+R2 |
| R1R2 |
| R1R2 |
| R1+R2 |