# Yu-Tsumura-small

by Yu · Published · Updated

Add to solve later

Add to solve later

Add to solve later

### More from my site

- The Rank and Nullity of a Linear Transformation from Vector Spaces of Matrices to Polynomials Let $V$ be the vector space of $2 \times 2$ matrices with real entries, and $\mathrm{P}_3$ the vector space of real polynomials of degree 3 or less. Define the linear transformation $T : V \rightarrow \mathrm{P}_3$ by \[T \left( \begin{bmatrix} a & b \\ c & d \end{bmatrix} \right) = […]
- Find All Matrices $B$ that Commutes With a Given Matrix $A$: $AB=BA$ Let \[A=\begin{bmatrix} 1 & 3\\ 2& 4 \end{bmatrix}.\] Then (a) Find all matrices \[B=\begin{bmatrix} x & y\\ z& w \end{bmatrix}\] such that $AB=BA$. (b) Use the results of part (a) to exhibit $2\times 2$ matrices $B$ and $C$ such that \[AB=BA \text{ and } […]
- The Existence of an Element in an Abelian Group of Order the Least Common Multiple of Two Elements Let $G$ be an abelian group. Let $a$ and $b$ be elements in $G$ of order $m$ and $n$, respectively. Prove that there exists an element $c$ in $G$ such that the order of $c$ is the least common multiple of $m$ and $n$. Also determine whether the statement is true if $G$ is a […]
- Every Group of Order 72 is Not a Simple Group Prove that every finite group of order $72$ is not a simple group. Definition. A group $G$ is said to be simple if the only normal subgroups of $G$ are the trivial group $\{e\}$ or $G$ itself. Hint. Let $G$ be a group of order $72$. Use the Sylow's theorem and determine […]
- Linear Dependent/Independent Vectors of Polynomials Let $p_1(x), p_2(x), p_3(x), p_4(x)$ be (real) polynomials of degree at most $3$. Which (if any) of the following two conditions is sufficient for the conclusion that these polynomials are linearly dependent? (a) At $1$ each of the polynomials has the value $0$. Namely $p_i(1)=0$ […]
- Find the Dimension of the Subspace of Vectors Perpendicular to Given Vectors Let $V$ be a subset of $\R^4$ consisting of vectors that are perpendicular to vectors $\mathbf{a}, \mathbf{b}$ and $\mathbf{c}$, where \[\mathbf{a}=\begin{bmatrix} 1 \\ 0 \\ 1 \\ 0 \end{bmatrix}, \quad \mathbf{b}=\begin{bmatrix} 1 \\ 1 […]
- Idempotent Matrix and its Eigenvalues Let $A$ be an $n \times n$ matrix. We say that $A$ is idempotent if $A^2=A$. (a) Find a nonzero, nonidentity idempotent matrix. (b) Show that eigenvalues of an idempotent matrix $A$ is either $0$ or $1$. (The Ohio State University, Linear Algebra Final Exam […]
- If a Group $G$ Satisfies $abc=cba$ then $G$ is an Abelian Group Let $G$ be a group with identity element $e$. Suppose that for any non identity elements $a, b, c$ of $G$ we have \[abc=cba. \tag{*}\] Then prove that $G$ is an abelian group. Proof. To show that $G$ is an abelian group we need to show that \[ab=ba\] for any […]