Chapter 3: Problem 7
Find a basis for the subspace \(S\) of \(\mathbb{R}^{4}\) consisting of all vectors of the form \((a+b, a-b+2 c, b, c)^{T}\) where \(a, b,\) and \(c\) are all real numbers. What is the dimension of \(S ?\)
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Chapter 3: Problem 7
Find a basis for the subspace \(S\) of \(\mathbb{R}^{4}\) consisting of all vectors of the form \((a+b, a-b+2 c, b, c)^{T}\) where \(a, b,\) and \(c\) are all real numbers. What is the dimension of \(S ?\)
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In each of the following, find the dimension of the subspace of \(P_{3}\) spanned by the given vectors: (a) \(x, x-1, x^{2}+1\) (b) \(x, x-1, x^{2}+1, x^{2}-1\) (c) \(x^{2}, x^{2}-x-1, x+1\) (d) \(2 x, x-2\)
Determine the null space of each of the following matrices: $$\text { (a) }\left[\begin{array}{ll} 2 & 1 \\ 3 & 2 \end{array}\right]$$ $$\text { (b) }\left[\begin{array}{rrrr} 1 & 2 & -3 & -1 \\ -2 & -4 & 6 & 3 \end{array}\right]$$ $$\text { (c) }\left[\begin{array}{rrr} 1 & 3 & -4 \\ 2 & -1 & -1 \\ -1 & -3 & 4 \end{array}\right]$$ $$\text { (d) }\left[\begin{array}{rrrr} 1 & 1 & -1 & 2 \\ 2 & 2 & -3 & 1 \\ -1 & -1 & 0 & -5 \end{array}\right]$$
Let \(A\) be a \(5 \times 8\) matrix with rank equal to 5 and let b be any vector in \(\mathbb{R}^{5}\). Explain why the system \(A \mathbf{x}=\mathbf{b}\) must have infinitely many solutions.
Let \(S\) be the subspace of \(P_{3}\) consisting of all polynomials of the form \(a x^{2}+b x+2 a+3 b\). Find a basis for \(S\).
Let \(A\) be a \(3 \times 3\) matrix and let \(\mathbf{x}_{1}, \mathbf{x}_{2},\) and \(\mathbf{x}_{3}\) be vectors in \(\mathbb{R}^{3}\). Show that if the vectors $$\mathbf{y}_{1}=A \mathbf{x}_{1}, \quad \mathbf{y}_{2}=A \mathbf{x}_{2}, \quad \mathbf{y}_{3}=A \mathbf{x}_{3}$$ are linearly independent, then the matrix \(A\) must be nonsingular and the vectors \(\mathbf{x}_{1}, \mathbf{x}_{2},\) and \(\mathbf{x}_{3}\) must be linearly independent.
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