Y = e ^ x y '= e ^ x can be written as y = f (x) and derivative y = f' (x) Y = x ^ 2, y = 2x written as y = f (x) and derivative y = f '(x)

Y = e ^ x y '= e ^ x can be written as y = f (x) and derivative y = f' (x) Y = x ^ 2, y = 2x written as y = f (x) and derivative y = f '(x)

It's OK for different functions. It's just a different notation of functions
But if in the same function, y and y 'are not equal, that is, y = f (x) and derivative y' = f '(x) are more accurate