If 2 functions g(x) & f(x) are defined so that (f ο g) (x) = x and (g ο f) (x) = x we say
that g(x) & f(x) are inverse functions of each other.
Functions f(x) & g(x) are inverses of each other in case the operations of g(x) reverse all the operations of f(x) in the reverse order & the operations of f(x) reverse all the operations of g(x) in the reverse order
The Best Example: Determine the inverse log function of f(x) = log(x + 5).
Solution: f(x) = log(x + 5)
We know that, f(f-1(x)) = x.
So, f(f-1(x + 5)) = log(f-1(x) + 5) = x
i.e., 10x = f-1(x) + 5 ( log10y = x => 10x = y )
f-1(x) = 10x - 5
This is the required inverse log function.
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