# Tagged Questions

For questions about the formulation of a proof, not about the mathematics behind it.

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### A proof that the Cantor set is Perfect

I found in a book a proof that the Cantor Set $\Delta$ is perfect, however I would like to know if "my proof" does the job in the same way. Theorem: The Cantor Set $\Delta$ is perfect. ...
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### Formalize a proof without words of the identity $(1 + 2 + \cdots + n)^2 = 1^3 + 2^3 + \cdots + n^3$

This website gives the following proof without words for the identity $(1 + 2 + \cdots + n)^2 = 1^3 + 2^3 + \cdots + n^3$. I find it interesting but have trouble seeing the proof behind it. Could ...
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### Proof of divisibility using modular arithmetic: $5\mid 6^n - 5n + 4$

Prove that: $$6^n - 5n + 4 \space \text{is divisible by 5 for} \space n\ge1$$ Using Modular arithmetic. Please do not refer to other SE questions, there was one already posted but it was using ...
I need a help with prooving that a given set is a convex set: $A \in \mathbb{R}^{m\times n}, c \in \mathbb{R}^n , b\in \mathbb{R}^m:$ $? \in argmin\{ c^Tx| Ax=b,x \geq 0\}$ I know the definition of ...