Inverse

An inverse function undoes the operation of the original function.

  • that is, the inverse function of a function f (also called the inverse of f) is a function that undoes the operation of f.

ex. imagine we have a function

f(x)=5x7f(x) = 5x − 7

One can think of ff as "the function which multiplies its input by 5 then subtracts 7 from the result". To undo this, one adds 7 to the input, then divides the result by 5.

Therefore, the inverse is

f(y)=(y+7)/5f(y) = (y + 7)/5

Celsius-Fahrenheit

Consider that the inverse of the formula to calculate C to F is the same formula to calculate F to C.

f(C)=95C+32f(C) = {9\over5C} + 32
f(F)=59(F32)f(F) = {5\over9}(F - 32)

Therefore, f(F) is the inverse of f(C), and f(C) is the inverse of f(F)


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