Let f denote a function that is continuous on the closed interval [a,b] and suppose f(a)!=f(b). If N is any number between f(a) and f(b), then there is at least one number c in (a,b) so that f(c)=N. But who is to stop me if I put it like this? Let f denote a function that is continuous on the open interval (a,b). Now, lim_(x->a^+)f(a)=L and lim_(x->b^−)f(b)=M. Suppose, L!=M. If N is any number between L and M, then there is at least one number c in (a,b) so that f(c)=N.

ajakanvao

ajakanvao

Answered question

2022-11-17

The statement for Intermediate Value Theorem is thus:

Let f denote a function that is continuous on the closed interval [ a , b ] and suppose f ( a ) f ( b ). If N is any number between f ( a ) and f ( b ), then there is at least one number c in ( a , b ) so that f ( c ) = N.

But who is to stop me if I put it like this?

Let f denote a function that is continuous on the open interval ( a , b ). Now, lim x a + f ( a ) = L and lim x b f ( b ) = M. Suppose, L M. If N is any number between L and M, then there is at least one number c in ( a , b ) so that f ( c ) = N.

Answer & Explanation

ontzeidena8a

ontzeidena8a

Beginner2022-11-18Added 17 answers

Nobody.
In fact, with f as in your suggestion, define g : [ a , b ] R ,
g ( x ) = { f ( x ) a < x < b L x = a M x = b
Then the classical IVT applied to g is equivalent to your variant applied to f. With this in mind, the standard formulation looks perhaps more appealing.
Jorge Schmitt

Jorge Schmitt

Beginner2022-11-19Added 5 answers

Your version follows from the previous version. Let F ( x ) = f ( x ) for a < x < b, F ( a ) = L and F ( b ) = M. Then F is continuous on [ a , b ] and the first version applied to F gives you the new version.

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