# Stanford-university-exam-eye-catch

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• Find a Value of a Linear Transformation From $\R^2$ to $\R^3$ Let $T:\R^2 \to \R^3$ be a linear transformation such that $T(\mathbf{e}_1)=\mathbf{u}_1$ and $T(\mathbf{e}_2)=\mathbf{u}_2$, where $\mathbf{e}_1=\begin{bmatrix} 1 \\ 0 \end{bmatrix}, \mathbf{e}_2=\begin{bmatrix} 0 \\ 1 \end{bmatrix}$ are unit vectors of $\R^2$ and […]
• Differentiation is a Linear Transformation Let $P_3$ be the vector space of polynomials of degree $3$ or less with real coefficients. (a) Prove that the differentiation is a linear transformation. That is, prove that the map $T:P_3 \to P_3$ defined by $T\left(\, f(x) \,\right)=\frac{d}{dx} f(x)$ for any $f(x)\in […] • Find an Orthonormal Basis of the Given Two Dimensional Vector Space Let$W$be a subspace of$\R^4$with a basis $\left\{\, \begin{bmatrix} 1 \\ 0 \\ 1 \\ 1 \end{bmatrix}, \begin{bmatrix} 0 \\ 1 \\ 1 \\ 1 \end{bmatrix} \,\right\}.$ Find an orthonormal basis of$W$. (The Ohio State […] • Powers of a Diagonal Matrix Let$A=\begin{bmatrix} a & 0\\ 0& b \end{bmatrix}$. Show that (1)$A^n=\begin{bmatrix} a^n & 0\\ 0& b^n \end{bmatrix}$for any$n \in \N$. (2) Let$B=S^{-1}AS$, where$S$be an invertible$2 \times 2$matrix. Show that$B^n=S^{-1}A^n S$for any$n \in […]
• Find All 3 by 3 Reduced Row Echelon Form Matrices of Rank 1 and 2 (a) Find all $3 \times 3$ matrices which are in reduced row echelon form and have rank 1. (b) Find all such matrices with rank 2.   Solution. (a) Find all $3 \times 3$ matrices which are in reduced row echelon form and have rank 1. First we look at the rank 1 case. […]
• A Basis for the Vector Space of Polynomials of Degree Two or Less and Coordinate Vectors Show that the set $S=\{1, 1-x, 3+4x+x^2\}$ is a basis of the vector space $P_2$ of all polynomials of degree $2$ or less.   Proof. We know that the set $B=\{1, x, x^2\}$ is a basis for the vector space $P_2$. With respect to this basis $B$, the coordinate […]
• Find All Values of $a$ which Will Guarantee that $A$ Has Eigenvalues 0, 3, and -3. Let $A$ be the matrix given by $A= \begin{bmatrix} -2 & 0 & 1 \\ -5 & 3 & a \\ 4 & -2 & -1 \end{bmatrix}$ for some variable $a$. Find all values of $a$ which will guarantee that $A$ has eigenvalues $0$, $3$, and $-3$.   Solution. Let $p(t)$ be the […]
• The Vector $S^{-1}\mathbf{v}$ is the Coordinate Vector of $\mathbf{v}$ Suppose that $B=\{\mathbf{v}_1, \mathbf{v}_2\}$ is a basis for $\R^2$. Let $S:=[\mathbf{v}_1, \mathbf{v}_2]$. Note that as the column vectors of $S$ are linearly independent, the matrix $S$ is invertible. Prove that for each vector $\mathbf{v} \in V$, the vector […]