Chapter 2: Problem 11
Prove that there exists a linear transformation \(T: R^{2} \rightarrow R^{3}\) such that \(\mathrm{T}(1,1)=(1,0,2)\) and \(\mathrm{T}(2,3)=(1,-1,4)\). What is \(\mathrm{T}(8,11)\) ?
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Chapter 2: Problem 11
Prove that there exists a linear transformation \(T: R^{2} \rightarrow R^{3}\) such that \(\mathrm{T}(1,1)=(1,0,2)\) and \(\mathrm{T}(2,3)=(1,-1,4)\). What is \(\mathrm{T}(8,11)\) ?
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Prove Theorem \(2.2(\) iii) and (iv): (iii) \((B+C) A=B A+C A\) (iv) \(k(A B)=(k A) B=A(k B)\)
Let \(\beta\) and \(\gamma\) be the standard ordered bases for \(\mathrm{R}^{n}\) and \(\mathrm{R}^{m}\), respectively. For each linear transformation \(\mathrm{T}: \mathrm{R}^{n} \rightarrow \mathrm{R}^{m}\), compute \([\mathrm{T}]_{\beta}^{\gamma}\). (a) \(\mathrm{T}: \mathrm{R}^{2} \rightarrow \mathrm{R}^{3}\) defined by $\mathrm{T}\left(a_{1}, a_{2}\right)=\left(2 a_{1}-a_{2}, 3 a_{1}+4 a_{2}, a_{1}\right)$. (b) \(\mathrm{T}: \mathrm{R}^{3} \rightarrow \mathrm{R}^{2}\) defined by $\mathrm{T}\left(a_{1}, a_{2}, a_{3}\right)=\left(2 a_{1}+3 a_{2}-a_{3}, a_{1}+a_{3}\right)$. (c) \(\mathrm{T}: \mathrm{R}^{3} \rightarrow R\) defined by \(\mathrm{T}\left(a_{1}, a_{2}, a_{3}\right)=2 a_{1}+a_{2}-3 a_{3}\). (d) \(\mathrm{T}: \mathrm{R}^{3} \rightarrow \mathrm{R}^{3}\) defined by $$ \mathrm{T}\left(a_{1}, a_{2}, a_{3}\right)=\left(2 a_{2}+a_{3},-a_{1}+4 a_{2}+5 a_{3}, a_{1}+a_{3}\right) . $$ (e) \(\mathrm{T}: \mathrm{R}^{n} \rightarrow \mathrm{R}^{n}\) defined by $\mathrm{T}\left(a_{1}, a_{2}, \ldots, a_{n}\right)=\left(a_{1}, a_{1}, \ldots, a_{1}\right)$. (f) \(\mathrm{T}: \mathrm{R}^{n} \rightarrow \mathrm{R}^{n}\) defined by $\mathrm{T}\left(a_{1}, a_{2}, \ldots, a_{n}\right)=\left(a_{n}, a_{n-1}, \ldots, a_{1}\right)$. (g) \(\mathrm{T}: \mathrm{R}^{n} \rightarrow R\) defined by \(\mathrm{T}\left(a_{1}, a_{2}, \ldots, a_{n}\right)=a_{1}+a_{n}\).
Label the following statements as true or false. (a) Suppose that \(\beta=\left\\{x_{1}, x_{2}, \ldots, x_{n}\right\\}\) and $\beta^{\prime}=\left\\{x_{1}^{\prime}, x_{2}^{\prime}, \ldots, x_{n}^{\prime}\right\\}\( are ordered bases for a vector space and \)Q$ is the change of coordinate matrix that changes \(\beta^{\prime}\)-coordinates into \(\beta\)-coordinates. Then the \(j\) th column of \(Q\) is \(\left[x_{j}\right]_{\beta^{\prime}}\). (b) Every change of coordinate matrix is invertible. (c) Let \(\mathrm{T}\) be a linear operator on a finite-dimensional vector space \(\mathrm{V}\), let \(\beta\) and \(\beta^{\prime}\) be ordered bases for \(\mathrm{V}\), and let \(Q\) be the change of coordinate matrix that changes \(\beta^{\prime}\)-coordinates into \(\beta\)-coordinates. Then \([\mathrm{T}]_{\beta}=Q[\mathrm{~T}]_{\beta^{\prime}} Q^{-1}\). (d) The matrices \(A, B \in \mathrm{M}_{n \times n}(F)\) are called similar if \(B=Q^{t} A Q\) for some \(Q \in \mathrm{M}_{n \times n}(F)\). (e) Let \(\mathrm{T}\) be a linear operator on a finite-dimensional vector space \(\mathrm{V}\). Then for any ordered bases \(\beta\) and \(\gamma\) for \(\mathrm{V},[\mathrm{T}]_{\beta}\) is similar to \([\mathrm{T}]_{\gamma}\).
Let \(V\) and \(W\) be vector spaces with subspaces \(V_{1}\) and \(W_{1}\), respectively. If \(\mathrm{T}: \mathrm{V} \rightarrow \mathrm{W}\) is linear, prove that \(\mathrm{T}\left(\mathrm{V}_{1}\right)\) is a subspace of \(\mathrm{W}\) and that $\left\\{x \in \mathrm{V}: \mathrm{T}(x) \in \mathrm{W}_{1}\right\\}\( is a subspace of \)\mathrm{V}$.
Define \(\mathrm{T}: \mathrm{M}_{2 \times 2}(R) \rightarrow \mathrm{P}_{2}(R) \quad\) by $\quad \mathrm{\top}\left(\begin{array}{ll}a & b \\ c & d\end{array}\right)=(a+b)+(2 d) x+b x^{2} .$ Let $$ \beta=\left\\{\left(\begin{array}{ll} 1 & 0 \\ 0 & 0 \end{array}\right),\left(\begin{array}{ll} 0 & 1 \\ 0 & 0 \end{array}\right),\left(\begin{array}{ll} 0 & 0 \\ 1 & 0 \end{array}\right),\left(\begin{array}{ll} 0 & 0 \\ 0 & 1 \end{array}\right)\right\\} \quad \text { and } \quad \gamma=\left\\{1, x, x^{2}\right\\} $$ Compute \([T]_{\beta}^{\gamma}\).
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