Chapter 4: Problem 11
Show that if \(A\) and \(B\) are similar matrices, then \(\operatorname{det}(A)=\operatorname{det}(B)\)
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Chapter 4: Problem 11
Show that if \(A\) and \(B\) are similar matrices, then \(\operatorname{det}(A)=\operatorname{det}(B)\)
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Let \(L\) be the linear operator mapping \(\mathbb{R}^{3}\) into \(\mathbb{R}^{3}\) defined by \(L(\mathbf{x})=A \mathbf{x},\) where $$A=\left(\begin{array}{rrr} 3 & -1 & -2 \\ 2 & 0 & -2 \\ 2 & -1 & -1 \end{array}\right)$$ and let $$\mathbf{v}_{1}=\left(\begin{array}{l} 1 \\ 1 \\ 1 \end{array}\right), \quad \mathbf{v}_{2}=\left(\begin{array}{l} 1 \\ 2 \\ 0 \end{array}\right), \quad \mathbf{v}_{3}=\left(\begin{array}{r} 0 \\ -2 \\ 1 \end{array}\right)$$ Find the transition matrix \(V\) corresponding to a change of basis from \(\left\\{\mathbf{v}_{1}, \mathbf{v}_{2}, \mathbf{v}_{3}\right\\}\) to \(\left\\{\mathbf{e}_{1}, \mathbf{e}_{2}, \mathbf{e}_{3}\right\\},\) and use it to determine the matrix \(B\) representing \(L\) with respect to \(\left\\{\mathbf{v}_{1}, \mathbf{v}_{2}, \mathbf{v}_{3}\right\\}\)
Show that if \(A\) is similar to \(B\) and \(A\) is nonsingular then \(B\) must also be nonsingular and \(A^{-1}\) and \(B^{-1}\) are similar.
Determine whether the following are linear transformations from \(C[0,1]\) into \(\mathbb{R}^{1}\) : (a) \(L(f)=f(0)\) (b) \(L(f)=|f(0)|\) (c) \(L(f)=[f(0)+f(1)] / 2\) (d) \(L(f)=\left\\{\int_{0}^{1}[f(x)]^{2} d x\right\\}^{1 / 2}\)
The trace of an \(n \times n\) matrix \(A,\) denoted \(\operatorname{tr}(A),\) is the sum of its diagonal entries; that is, $$\operatorname{tr}(A)=a_{11}+a_{22}+\cdots+a_{n n}$$ Show that (a) \(\operatorname{tr}(A B)=\operatorname{tr}(B A)\) (b) if \(A\) is similar to \(B,\) then \(\operatorname{tr}(A)=\operatorname{tr}(B)\)
Find the standard matrix representation for each of the following linear operators: (a) \(L\) is the linear operator that rotates each \(\mathbf{x}\) in \(\mathbb{R}^{2}\) by \(45^{\circ}\) in the clockwise direction. (b) \(L\) is the linear operator that reflects each vector \(\mathbf{x}\) in \(\mathbb{R}^{2}\) about the \(x_{1}\) -axis and then rotates it \(90^{\circ}\) in the counterclockwise direction. (c) \(L\) doubles the length of \(\mathbf{x}\) and then rotates it \(30^{\circ}\) in the counterclockwise direction. (d) \(L\) reflects each vector \(\mathbf{x}\) about the line \(x_{2}=x_{1}\) and then projects it onto the \(x_{1}\) -axis.
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