Rudy the Reindeer
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 Feb 9 comment Find the matrix representing T and Find the Image of T (as a span of vectors) The matrix you found is correct. The image of $T$ is the span of the columns of $A$. Feb 7 revised For what $n$ is $U_n$ cyclic? spelling fixed Feb 5 comment Check the proof of $||x||^2$ is not a norm @ElChapo Her question is "Can someone check my proof for correctness" Feb 5 comment Check the proof of $||x||^2$ is not a norm Yes, that's all correct. You didn't have to do the third case: after 2) you already know that it is not a norm. Jan 30 comment A question about a proof of Noetherian modules and exact sequences I don't think a proof-verification can be a duplicate of a newer question. Unless someone posts the exact same proof with the exact same mistakes. Jan 30 revised A question about a proof of Noetherian modules and exact sequences edited tags Jan 30 revised A question about a proof of Noetherian modules and exact sequences rolled back to a previous revision Jan 27 revised A question about a proof of Noetherian modules and exact sequences Image removed and replaced with text. Jan 25 awarded Popular Question Jan 25 awarded algebraic-topology Jan 22 comment Is the space $C[0,1]$ complete? @karhas Yes, that's right: it's definitely needed in the proof that $f$ is the uniform limit of the $f_n$. Jan 19 revised Nonzero rationals under multiplication are not a cyclic group added 4 characters in body Jan 19 revised Show that the set of non zero rationals is not a cyclic group under multiplication. edited tags Jan 19 revised Characterize the groups $G$ for which the map $\iota: G \to G$, sending $x \mapsto x^{-1}$ for all $x \in G$, is an automorphism of $G$ added 11 characters in body Jan 15 answered Question about the $\limsup$ of a bounded function on [0,1) Jan 13 awarded Yearling Jan 12 awarded Nice Question Jan 12 awarded Popular Question Jan 10 comment $a\mid b$ and $b\mid a$ but $a$ and $b$ are not associates I couldn't find a definition of associates (other what's in @frogeyedpeas' link and there it's the same as $a\mid b$ and $b \mid a$). Can you include a definition in your question? Jan 10 awarded Nice Answer