\(\text{M}< \frac{1}{12}\)
https://olm.vn/hoi-dap/detail/104825592969.html
https://olm.vn/hoi-dap/detail/104825592969.html
https://olm.vn/hoi-dap/detail/104825592969.html
https://olm.vn/hoi-dap/detail/104825592969.html
https://olm.vn/hoi-dap/detail/104825592969.html
https://olm.vn/hoi-dap/detail/104825592969.html
\(M=\frac{1}{12}\)