Is g(x) Always Continuous if Sandwiched Between Two Continuous Functions?

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SUMMARY

The discussion confirms that a function g(x) does not have to be continuous even if it is sandwiched between two continuous functions f(x) and h(x). The examples provided include f(x) = sin(x) - 3, h(x) = sin(x) + 3, and g(x) = sin(1/x), which demonstrates that g(x) is discontinuous at x = 0. Another example given is the signum function and a function that takes the value 1 for rational x and 2 for irrational x, both of which illustrate discontinuity despite the continuity of f and h.

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Homework Statement



If f(x) < g(x) < h(x) for all x E R, and if f and h are continuous functions, must g also be continuous? If so, why? If not, can you come up with a counter example?

What do you think?
 
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Hi...
For the given conditions ,the function g need not be continuous.
Example : f(x) = sin(x) - 3 , h(x) = sin(x) + 3 , g(x) = sin(1/x)
for this example , f(x) < g(x) < h(x) . f and h are continuous . But g is not continuous at x tends to 0. Instead of g(x) = sin(1/x) , u can also take a signum function which is not continuous at x = 0.
 
Blazeatron's example is sufficient but simpler-
f(x)= 0 for all x, h(x)= 3 for all x, g(x)= 1 if x is rational, 2 if x is irrational. g is discontinuous for all x.
 

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