Chapter 3: Problem 1
Determine whether each of the following equations is linear: (a) \(5 x+7 y-8 y z=16\) (b) \(x+\pi y+e z=\log 5\) (c) \(3 x+k y-8 z=16\)
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Chapter 3: Problem 1
Determine whether each of the following equations is linear: (a) \(5 x+7 y-8 y z=16\) (b) \(x+\pi y+e z=\log 5\) (c) \(3 x+k y-8 z=16\)
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Reduce each of the following matrices to echelon form and then to row canonical form: (a) \(\left[\begin{array}{rrr}1 & 1 & 2 \\ 2 & 4 & 9 \\ 1 & 5 & 12\end{array}\right]\) (b) \(\left[\begin{array}{rrrrr}1 & 2 & -1 & 2 & 1 \\ 2 & 4 & 1 & -2 & 5 \\ 3 & 6 & 3 & -7 & 7\end{array}\right]\) (c) \(\left[\begin{array}{rrrrrr}2 & 4 & 2 & -2 & 5 & 1 \\ 3 & 6 & 2 & 2 & 0 & 4 \\ 4 & 8 & 2 & 6 & -5 & 7\end{array}\right]\)
Let \(A=\left[\begin{array}{rrrr}2 & -2 & 2 & 1 \\ -3 & 6 & 0 & -1 \\ 1 & -7 & 10 & 2\end{array}\right] .\) Reduce \(A\) to echelon form using the pivoting algorithm.
Describe the pivoting row-reduction algorithm. Also describe the advantages, if any, of using this pivoting algorithm.
Show that every elementary matrix \(E\) is invertible, and its inverse is an elementary matrix.
Use Gaussian elimination to solve the following systems of linear equations. \(x_{1}+2 x_{2}-x_{3}=-1\) (a) \(2 x_{1}+2 x_{2}+x_{3}=1\) (b) $\begin{aligned} x_{1}-2 x_{2}-x_{3} &=1 \\ 2 x_{1}-3 x_{2}+x_{3} &=6 \\\ 3 x_{1}-5 x_{2} &=7 \\ x_{1}+5 x_{3} &=9 \end{aligned}$ \(3 x_{1}+5 x_{2}-2 x_{3}=-1\) \(x_{1}+2 x_{2}+2 x_{4}=6\) (c) \(3 x_{1}+5 x_{2}-x_{3}+6 x_{4}=17\) \(2 x_{1}+4 x_{2}+x_{3}+2 x_{4}=12\) \(2 x_{1} \quad-7 x_{3}+11 x_{4}=7\) \(x_{1}-x_{2}-2 x_{3}+3 x_{4}=-63\) (d) \(2 x_{1}-x_{2}+6 x_{3}+6 x_{4}=-2\) \(-2 x_{1}+x_{2}-4 x_{3}-3 x_{4}=0\) \(3 x_{1}-2 x_{2}+9 x_{3}+10 x_{4}=-5\) \(x_{1}-4 x_{2}-x_{3}+x_{4}=3\) (f) \(x_{1}+2 x_{2}-x_{3}+3 x_{4}=2\) (e) \(2 x_{1}-8 x_{2}+x_{3}-4 x_{4}=9\) (f) \(2 x_{1}+4 x_{2}-x_{3}+6 x_{4}=5\) \(-x_{1}+4 x_{2}-2 x_{3}+5 x_{4}=-6\) \(x_{2}+2 x_{4}=3\) \(2 x_{1}-2 x_{2}-x_{3}+6 x_{4}-2 x_{5}=1\) (g) \(\quad x_{1}-x_{2}+x_{3}+2 x_{4}-x_{5}=2\) \(4 x_{1}-4 x_{2}+5 x_{3}+7 x_{4}-x_{5}=6\)Sec. \(3.4\) Systems of Linear Equations-Computational Aspects $$ \begin{aligned} 3 x_{1}-x_{2}+x_{3}-x_{4}+2 x_{5} &=5 \\ \text { (h) } x_{1}-x_{2}-x_{3}-2 x_{4}-x_{5} &=2 \\ 5 x_{1}-2 x_{2}+x_{3}-3 x_{4}+3 x_{5} &=10 \\ 2 x_{1}-x_{2}-2 x_{4}+x_{5} &=5 \\ 3 x_{1}-x_{2}+2 x_{3}+4 x_{4}+x_{5} &=2 \\ \text { (i) } x_{1}-x_{2}+2 x_{3}+3 x_{4}+x_{5} &=-1 \\ 2 x_{1}-3 x_{2}+6 x_{3}+9 x_{4}+4 x_{5} &=-5 \\ 7 x_{1}-2 x_{2}+4 x_{3}+8 x_{4}+x_{5} &=6 \\ 2 x_{1}+3 x_{3}-4 x_{5} &=5 \\ 3 x_{1}-4 x_{2}+8 x_{3}+3 x_{4} &=8 \\ x_{1}-x_{2}+2 x_{3}+x_{4}-x_{5} &=2 \\ -2 x_{1}+5 x_{2}-9 x_{3}-3 x_{4}-5 x_{5} &=-8 \end{aligned} $$
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