Найти D (f) если f(x) = корень из -5/х^2 +3х - х-1/х+1

Advantages: 1. You can study longer than others, who wants to sleep

2. You can read a lot of books
3. You dont waste your time to sleeping
disadvantages: 1. You always feel tired
2. It can badly affect on your health
3. You will have a patient view