Theorem 5.3.2: Continuous functions map compact sets to compact sets. (d) If f2 is continuous on D then f is continuous on D.
(a) Suppose f(x) is continuous on the closed interval [02] and f(0) = f(2). Note that f(x + 1) is defined on If g(0) = 0
The maximum value of f is 1/? attained at x = 2/?. Finally
A function f : X ? Y is said to be continuous if the inverse image of every open subset of Y is open in X. In other words if V ? TY
then f is said to be continuous at x = c. 5.1.2 Continuity in an interval. (i) f is said to be continuous in an open interval (a b) if it is continuous at
If f : (a b) ? R is defined on an open interval
x0 /? E. Show that there is an unbounded continuous function f : E ? R. Show that if f1f2
Example 2 : Suppose f is continuous on [a b] and differentiable on (a
19 sept. 2012 (Composition) If f : X ? Y and g : Y ? Z are continuous then g ? f : X ? Z is continuous. ... Proof of (2) - Inclusion is continuous.
j=1Fj. The function f is continuous on F which is a finite union of If [ti?1
it is not continuous at x= 0 Theorem 2: Suppose both f(x) and g(x) are continuous at x= a Then: (a) f+ g f g and fgare continuous at x= a (b) If g(a) 6= 0 then f=gis continuous at x= a Theorem 3: If fis continuous at a and if gis continuous at f(a) then f g is continuous at a Intermediate Value Theorem (IVT): Suppose fis continuous on
continuity of f2 at y The function f is continuous at c if f(x) ? f(c) as x ? c The restriction f1 is continuous at c if f(x) ? f(c) as x ? c? The restriction f2 is continuous at c if f(x) ? f(c) as x ? c+ Therefore f is continuous at c if and only if both f1 and f2 are continuous at c Example The function f(x) = x is
A function f is said to be continuous on an interval if it is continuous at each and every point in the interval Continuity at an endpoint if one exists means f is continuous from the right (for the left endpoint) or continuous from the left (for the right endpoint) ex f ( x) = 1/ x is continuous on (? ? 0) and on (0 ?) ex f ( x
Show that there exists a continuous function F: [a;b] !R such that F(x) = f(x) for all x2(a;b) if and only if fis uniformly continuous Hint Given f how should you de ne F(a) and F(b)? Solution: Consider the sequence x n= a+ 1=n For large enough n a n2(a;b) Since fa ng is Cauchy and since f is uniformly continuous by part(a) ff(a
above displayed formula jf(x) f(y)j 4jx yj