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1d
comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
@GitGud, Thanks for the additional info!
1d
accepted Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
1d
comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
Great answer, Thanks!
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comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
@GitGud rank$(BA) \le n$? But $BA_{n \times n}$ so how does that help?
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comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
@GitGud, Ok, so for $A=0$ it contridicts AB, how about BA then?
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revised Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
added 216 characters in body
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comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
@DavidButlerUofA: Let me try rephrase, maybe I made a mistake translating the question: Given $A_{m\times n}$ and $B_{n \times m} (m<n)$.1) Is AB Singular?2) Is BA Singular? My answers say that 1 is false and 2 is true.
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awarded  Custodian
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reviewed Approve suggested edit on Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
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comment Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
@DavidButlerUofA: No, the question does not state that, but the question is that for -every- $A , B$ it happens, so you can't pick $A=0$
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asked Given $A_{m\times n}$ and $B_{n \times m} (m<n)$. prove that AB is not singular and BA is singular
1d
comment Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
@you-sir-33433: yea thanks, I have been reading up a bit on this, found out about synthetic division and how to use it with quadratic expression. This seems like the quickest way to do it.
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accepted Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
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comment Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
@MohammadKhosravi: I did not understand your trick :) English is not my first language (despite my name ;p) what are monomial?
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comment Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
@RobertLewis: Thanks a lot. Now I got it.
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comment Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
@Thanks for the detailed answer. I seem to have trouble coming up with the division you did in step (2). Is there any trick I can use for that?
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asked Given that $i$ is a root of: $P(x)=x^4 + 2x^3+ 3x^2 + 2x+2$ find all the other roots
Jul
5
revised Proving Linear Dependency of A based of $ (SpA)^\perp = \{(a,a-b,b-c,a)\mid a,b,c \in R\} $
Changed dim to \dim
Jul
5
suggested suggested edit on Proving Linear Dependency of A based of $ (SpA)^\perp = \{(a,a-b,b-c,a)\mid a,b,c \in R\} $
Jul
5
comment Proving Linear Dependency of A based of $ (SpA)^\perp = \{(a,a-b,b-c,a)\mid a,b,c \in R\} $
Hmm, Thanks for the hint, but I find myself unable to answer those questions