Bài 1:

1)`56.712-7.50.80-7.12.8`

`=56.712-7.50.8.10-56.12`

`=56.712-56.500-56.12`

`=56.(712-500-12)`

`=56.200`

`=11200`

2)`5^0:3/((-1)^2024)+(6 1/6-2 4/9. 2 5/11)`

`=1:3/1+(37/6-22/9. 27/11)`

`=1/3+(37/6-6)`

`=1/3+1/6`

`=1/2`

3)`1/2.6+1/4.9+1/6.12+...+1/36.57+1/38.60`

`=1/6.(1/1.2+1/2.3+1/3.4+...+1/18.19+1/19.20)`

`=1/6.(1-1/2+1/2-1/3+1/3-1/4+...+1/18-1/19+1/19-1/20)`

`=1/6.(1-1/20)`

`=1/6. 19/20`

`=19/120`