Mathematics Stack Exchange
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Questions tagged [solution-verification]

For posts looking for feedback or verification of a proposed solution. "Is my proof correct?" is too broad or missing context. Instead, the question must identify precisely which step in the proof is in doubt, and why so. This should not be the only tag for a question, and should not be used to circumvent site policies regarding duplicate questions.

This tag should be used when you have a proposed solution to a problem and have specific concerns or doubts about the validity of that solution. A question with this tag should include an explanation for why the argument presented is not convincing enough. Further discussion on using this tag can be found in the Mathematics Meta questions (1) and (2).

Answers to questions tagged look first and foremost to check that the solution is right, and to comment upon the approach taken by the author of the question. If the proposed solution is wrong, a good answer would explain where or how mistakes were made, and possibly give or sketch a correct solution instead.

If the proposed solution is correct, an answer would ideally provide further evidence to back the answerer's opinion. These could include a clearer rewriting of the given argument, alternative arguments, generalizations of the proven result, or careful consideration of unexpected subtle points. Users looking to write answers can find further discussion in this Mathematics Meta post.

21426 questions
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High school olympiad homogeneity $\frac{a}{b+2c}+\frac{b}{c+2a}+\frac{c}{a+2b} \geq 1$

Problem: Prove for $a,b,c \in \mathbb{R+}$\begin{split} \frac{a}{b+2c}+\frac{b}{c+2a}+\frac{c}{a+2b} \geq 1 \end{split} Solution: Assume $x = b+2c, y = c+2a, z = a+2b$. Rewrite left side to \begin{split}…
Csaba Daniel Farkaš
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Prove that every positive integer can be expressed as a product of odd number and power of 2.

This is what I am trying to prove: Prove that every positive integer $n$ can be expressed as the product of an odd number and a power of $2$, that is, for every $n ≥ 1$ there are $h$ in $Z^+$, $h$ odd and $k$ in $Z$, $k ≥ 0$ such that $n = h· 2^k$.…
AMM
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The space of continuous function with compact support and a norm on it.

Denote with $C_0(\Omega)$ the subspace of countinuous functions with compact support, $\Omega\subseteq\mathbb{R}^n$ open. Define an application on $C_0(\Omega)$ as $||\cdot||\colon C_0(\Omega)\to\mathbb{R}_+$ $$||f||_1:=\int_\Omega |f|\;d\lambda_n$$…
Jack J.
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Existence of Least Upper Bounds (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
user10360304
  • 399
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Infimums, Supremums, and Ordered Sets (Proof Verification)

I'm practicing my proof-writing and was hoping you could let me know if this proof looks good. I would like to know if the proof is incorrect, if there are parts that are overly wordy/complicated, or if I'm missing some element of a proof that is…
user10360304
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Let $a,b\in\mathbb N, a\gt b\gt 2$. Prove that $b^{a}\gt a^{b},\forall a,b$.

Let $a,b\in\mathbb N, a\gt b\gt 2$. Prove that $b^{a}\gt a^{b},\forall a,b$. This is a relatively new question, so this may or may not be true. Does anyone know if this is true or not?
Hinson Chan
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Fermat' Last Theorem

Fermat‘s Last Theorem Fermat‘s last theorem (proofed by Andrew Wiles in 1994) a^(i) – b^(i) <> c^(i) a, b, c, i are elements of N with a > b, i >1, i<>2; a, b, c are coprime. I) We start the proof with exponent i=3 If a³ – b³ = c³ then: c³ =…
miwis
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Proof of a Logical Statement.

Prove that $A \cap B$ is a subset of $A$. Would I go around this by saying that $S \subseteq A$ and then by hypothesis belongs to $B$ as well? Or would I do it with values of $X$?
Hunter Mortleman
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Counterexample for a statement

Lets say I want to prove or disprove the statement $p \to q$. If I show that $p\to \lnot q$ for one particular case, isn't that a counterexample that shows that the statement is false?
Pink Panda
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Is $x^2 \equiv y^3 \pmod 4$ an equivalence relation on the set of all integers?

I know $x \equiv y \pmod n$ is an equivalence relation in general but does squaring or cubing change that?
Isaac Jaynes
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Proof By Induction: Correct?

I try to prove that: Statement (S): $\frac{1}{n-1}(1-\frac{1}{n}) = \frac{1}{n}$ by induction for all $\forall n \in \mathbb{N} \setminus$ {$ 1 $}. Here is my solution: Base case: S(2) $ = \frac{1}{2-1} (1 - \frac{1}{2}) = \frac{1}{1} - \frac{1}{2}…
user2550228
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prove bit mask is unique

If $(\cdot)$ is the bitwise XOR operation and $X$ and $Y$ are any two binary numbers, then $Z$ is the bitmask such that: \begin{align}X(\cdot)Y&=Z \\ X(\cdot)Z&=Y\\ Y(\cdot)Z&=X \end{align} Now how do I prove that: For some $W$ (a binary…
juztcode
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Where does proof of $(b^x)^y=b^{xy}$ for $b<0$ fail?

Here's a proof: $$\left(b^{x}\right)^{y}=\exp\left[y\left(\ln b^{x}\right)\right]=\exp\left[xy\left(\ln b\right)\right]=b^{xy}$$ But if for example $b=-1$, then $(b^2)^{1/2}=1$, while $b^{2\times1/2}=b^1=-1$, so that $(b^x)^y\neq b^{xy}$. So where…
user693894
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for question about combinatorials

on reading the following proof , I understand the reduction in the number of terms by using the "telescoping " method. My concern is terms such as the second term in: $1\choose k+1$-$0\choose k+1$ which appears twice , is this a valid…
ralph
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Is my proof of injunctions onto $\mathbb{N}_n$ correct?

The question: suppose $S$ is a set and $f(s): S \rightarrow \mathbb{N}_n$ is an injection. Then $|S|$ must be finite. My proof: I will proceed by contradiction. Presume that $|S|$ is infinite. By the definition of an injection, every $s\in S$…
Michael Stachowsky
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