Questions tagged [proof-writing]

For questions about the formulation of a proof. This tag should not be the only tag for a question and should not be used to ask for a proof of a statement.

10,080 questions
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Area related question for an equilateral triangle

The question is Let $ABC$ be an equilateral triangle with side $a$. $M$ is a point such that $MS=d$ where $S$ is the centre of $\Delta ABC$. Prove that the area of the triangle whose sides are of ...
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Issues in understanding proof for: The existence of irrational roots — a consequence of completeness.

Have difficulty in understanding the proof below, in the book, by Traynor, titled: Introduction_to_analysis, at page #27; with title: The existence of roots — a consequence of completeness. The proof ...
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“Prove that ∂A ∪ Int(A) = Cl(A)” [duplicate]

The question comes from “Introduction to Topology: Pure and Applied” by Colin Adams and Robert Franzosa. I have very little knowledge of set theory and proofs, so I'm not sure how to prove this. As ...
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Prove that $\partial A = \mathrm{Cl}(A) \cap \mathrm{Cl}(X − A)$

My textbook doesn't give me the fact that $\partial A = \mathrm{Cl}(A) \cap \mathrm{Cl}(X − A)$. We're asked to prove it. I'm given $\partial A = \mathrm{Cl}(A) − \mathrm{Int}(A)$. In a previous ...
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Fundemental Properties of Well-Ordering (Checking My Answers)

Give two different examples of well-ordered sets one of which is infinite. My Answer: $\mathbb{N}$ and $\left\{0\right\}$. Show that every subset of a well ordered set is a well ordered set with ...
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“Prove that Cl(ℚ) = ℝ in the standard topology on ℝ.” [duplicate]

I have very little knowledge of set theory and proof writing. This is a problem from “Introduction to Topology: Pure and Applied” by Colin Adams and Robert Franzosa. INFORMATION GIVEN Consider the ...
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