bhori
commented
4 years ago You right, but the best thing we can do is to chek the values of f(x) for several values of x ,we can choose random and ordered values to accurately test and it will give us an indication if this functions are equal or not. I know it is not perfect but in most cases it should work.
We do not know the scope and origin of the functions, so we cannot know if they are 100 percent equal. It is possible to check the values of f(x), but you cannot check them all, so even if we test a lot and match all these values, it does not mean that the functions are equal.