If variance is 0, then p(x=c) = 1 c is constant

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I think it is easy but I can't figure it out. :(
any help?
 
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Are you trying to prove or disprove the thread title?

Is this homework?
 
You may suppose that the expectation is zero, you know, that makes it (even) easier.
 
I would advise figuring out what you're trying to prove before working on the proof. (The sentence in the title is not a well-posed question!)
 

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