Let f and g be periodic functions with the periods T₁ and T₂ respectively. Then f + g is

Consider the function $$y = {\log _a}(x + \sqrt {{x^2} + 1} ),a > 0,a \ne 1$$. The inverse of the function

Let f : X $$ \to $$ X be such that f [f(x)] = x, for all x$$\in$$X and X$$ \subseteq $$R, then