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Mathematics)

Given a function f(x), its inverse function is written as f^{-1}(x).

An inverse function is one which reverses the job of the original function, for instance if

f(x) = 2x + 3

Then

f^{-1}(x) = (x-3) / 2

f(3) = (2 * 3) + 3 = 9

f^{-1}(9) = (9 - 3) / 2 = 3

Finding an inverse function for any given function is a process of 'undoing' each operation of the original function in reverse order. For instance, f(x) above multiplied by 2 and then added 3. The inverse undid this the other way around - ot subtracted 3 then divided by 2.