It is known that the domain of the function FX is the domain of - 1,1 to find f (x + 2) + F (x + 1)

It is known that the domain of the function FX is the domain of - 1,1 to find f (x + 2) + F (x + 1)

The domain of F (x) is - 1,1, that is - 1 < x < 1
The definition of F (x + 2) is: - 1 < x + 2 < 1, that is - 3 < x < - 1
The domain of F (x + 1) is: - 1 < x + 1 < 1, that is: - 2 < x < 0
The definition field of F (x + 2) + F (x + 1) is: - 2 < x < - 1