Given f(x) =√x+1​ and g(x) =∣x∣, find their natural domain and formulas for:
(a) (f+g) (x)
(b) (f−g) (x)
(c) (f⋅g) (x)
(d) (gf​) (x) (e) (f∘g) (x) (f) (g∘f) (x)