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kingwinner
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Homework Statement
Show that the closed unit ball {x E V:||x||≤1} of a normed vector space, (V,||.||), is convex, meaning that if ||x||≤1 and ||y||≤1, then every point on the line segment between x and y has norm at most 1.
(hint: describe the line segment algebraically in terms of x and y and a parameter t.)
Homework Equations
The Attempt at a Solution
For the line segment between x and y, is it described by x+t(y-x), 0≤t≤1? I'm pretty sure this is correct in [tex]R^n[/tex], but is it still true in a general normed vector space? Does it still describe a straight line? Why or why not?
Also, how can we prove that the norm of it is ≤1?
Thanks!