Chapter 4: Problem 46
Prove Theorem 4.8: Suppose \(A\) and \(B\) are row canonical matrices. Then \(A\) and \(B\) have the same row space if and only if they have the same nonzero rows.
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Chapter 4: Problem 46
Prove Theorem 4.8: Suppose \(A\) and \(B\) are row canonical matrices. Then \(A\) and \(B\) have the same row space if and only if they have the same nonzero rows.
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Find a basis and the dimension of the subspace \(W\) of \(V=\mathbf{M}_{2,2}\) spanned by \\[A=\left[\begin{array}{rr} 1 & -5 \\ -4 & 2 \end{array}\right], \quad B=\left[\begin{array}{rr} 1 & 1 \\ -1 & 5 \end{array}\right], \quad C=\left[\begin{array}{rr} 2 & -4 \\ -5 & 7 \end{array}\right], \quad D=\left[\begin{array}{rr} 1 & -7 \\ -5 & 1 \end{array}\right]\\]
Let \(V\) be the set of ordered pairs \((a, b)\) of real numbers. Show that \(V\) is not a vector space over \(\mathbf{R}\) with addition and scalar multiplication defined by (i) \((a, b)+(c, d)=(a+d, b+c)\) and \(k(a, b)=(k a, k b)\), (ii) \((a, b)+(c, d)=(a+c, b+d)\) and \(k(a, b)=(a, b)\), (iii) \((a, b)+(c, d)=(0,0)\) and \(k(a, b)=(k a, k b)\), (iv) \(\quad(a, b)+(c, d)=(a c, b d)\) and \(k(a, b)=(k a, k b)\).
Suppose \(W_{1}, W_{2}, \ldots, W_{r}\) are subspaces of a vector space \(V\). Show that (a) \(\operatorname{span}\left(W_{1}, W_{2}, \ldots, W_{r}\right)=W_{1}+W_{2}+\cdots+W_{r}\). (b) If \(S_{i}\) spans \(W_{i}\) for \(i=1, \ldots, r,\) then \(S_{1} \cup S_{2} \cup \ldots \cup S_{r}\) spans \(W_{1}+W_{2}+\cdots+W_{r}\).
In the space \(\mathbf{M}=\mathbf{M}_{2,3},\) determine whether or not the following matrices are linearly dependent: \(A=\left[\begin{array}{lll}1 & 2 & 3 \\ 4 & 0 & 5\end{array}\right], \quad B=\left[\begin{array}{rrr}2 & 4 & 7 \\ 10 & 1 & 13\end{array}\right], \quad C=\left[\begin{array}{rrr}1 & 2 & 5 \\ 8 & 2 & 11\end{array}\right]\) If the matrices are linearly dependent, find the dimension and a basis of the subspace \(W\) of \(\mathbf{M}\) spanned by the matrices.
Show that \(\operatorname{span}(S)=\operatorname{span}(S \cup\\{0\\}) .\) That is, by joining or deleting the zero vector from a set, we do not change the space spanned by the set.
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