- #1
shotputer
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Homework Statement
Let a function f : R => R be convex. Show that f is necessarily continuous. Hence, there can be no convex functions that are not also continuous.
Homework Equations
The Attempt at a Solution
F is continuos if there exist [tex]\epsilon[/tex] >0 and [tex]\delta[/tex]>0 such that |x-y|< [tex]\delta[/tex] => |f(x) - f(y)| <[tex]\epsilon[/tex]
on the other hand function is convex if for some numbers a and b, with a<b an [tex]\lambda[/tex] [tex]E[/tex] (0,1) f( [tex]\lambda[/tex] a+ (1-[tex]\lambda[/tex] b) [tex]\leq[/tex] [tex]\lambda[/tex] f(a) + (1-[tex]\lambda[/tex]) f(b)
so basicaly that is what I have, I got hint that we should use this definition of continuity... but I don't have idea where to start...
help, pleease...