Chapter 1: Problem 11
Give a geometrical interpretation of a linear equation in three unknowns. Give a geometrical description of the possible solution sets for a \(3 \times 3\) linear system.
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Chapter 1: Problem 11
Give a geometrical interpretation of a linear equation in three unknowns. Give a geometrical description of the possible solution sets for a \(3 \times 3\) linear system.
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For each of the following, answer true if the statement is always true and answer false otherwise. In the case of a true statement, explain or prove your answer. In the case of a false statement, give an example to show that the statement is not always true. If \(E\) and \(F\) are elementary matrices and \(G=E F\) then \(G\) is nonsingular
Let \(A=\left[\begin{array}{ll}A_{11} & A_{12} \\ A_{21} & A_{22}\end{array}\right] \quad\) and \(\quad A^{T}=\left[\begin{array}{cc}A_{11}^{T} & A_{21}^{T} \\ A_{12}^{T} & A_{22}^{T}\end{array}\right]\) Is it possible to perform the block multiplications of \(A A^{T}\) and \(A^{T} A ?\) Explain.
For each of the pairs of matrices that follow, determine whether it is possible to multiply the first matrix times the second. If it is possible, perform the multiplication. (a) \(\left[\begin{array}{rrr}3 & 5 & 1 \\ -2 & 0 & 2\end{array}\right]\left[\begin{array}{ll}2 & 1 \\ 1 & 3 \\ 4 & 1\end{array}\right]\) (b) \(\left[\begin{array}{cc}4 & -2 \\ 6 & -4 \\ 8 & -6\end{array}\right]\left[\begin{array}{lll}1 & 2 & 3\end{array}\right]\) (c) \(\left[\begin{array}{lll}1 & 4 & 3 \\ 0 & 1 & 4 \\ 0 & 0 & 2\end{array}\right]\left[\begin{array}{ll}3 & 2 \\ 1 & 1 \\ 4 & 5\end{array}\right]\) (d) \(\left[\begin{array}{ll}4 & 6 \\ 2 & 1\end{array}\right]\left[\begin{array}{lll}3 & 1 & 5 \\ 4 & 1 & 6\end{array}\right]\) (e) \(\left[\begin{array}{lll}4 & 6 & 1 \\ 2 & 1 & 1\end{array}\right]\left[\begin{array}{lll}3 & 1 & 5 \\ 4 & 1 & 6\end{array}\right]\) (f) \(\left[\begin{array}{r}2 \\ -1 \\\ 3\end{array}\right]\left[\begin{array}{llll}3 & 2 & 4 & 5\end{array}\right]\)
Let \(A=\left(\begin{array}{lll}1 & 2 & 4 \\ 2 & 1 & 3 \\ 1 & 0 & 2\end{array}\right), \quad B=\left(\begin{array}{lll}1 & 2 & 4 \\ 2 & 1 & 3 \\\ 2 & 2 & 6\end{array}\right)\) \(C=\left(\begin{array}{rrr}1 & 2 & 4 \\ 0 & -1 & -3 \\ 2 & 2 & 6\end{array}\right)\) (a) Find an elementary matrix \(E\) such that \(E A=B\) (b) Find an elementary matrix \(F\) such that \(F B=C\) (c) Is \(C\) row equivalent to \(A\) ? Explain.
For each of the following, answer true if the statement is always true and answer false otherwise. In the case of a true statement, explain or prove your answer. In the case of a false statement, give an example to show that the statement is not always true. If \(A\) is row equivalent to \(I\) and \(A B=A C\), then \(B\) must equal \(C\)
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