a & gt0; |-a | = a；
a-b & gt； 0; | a-b | = a-b；
| a | & lt| b || a+b | =-b-a；
The original formula =-b-a+a-b+(-b-a) =-3b-a;
- 1/2- 1/6- 1/ 12- 1/20- 1/30- 1/42- 1/56- 1/72- 1/90- 1/ 10=- 1
Deeply reflect on the final exam summary 800 words 1
This test is of great significance to highlight