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Section 3.6 Solving General \(\A\x=\b:\) Homework

Exercises Exercises

Exercise Group.

Find the solution set to \(\A\x=\b\) for each of the following, citing any theorems you use.
For any system having exactly one solution, write the linear combination of the columns of \(\A\) which equals \(\b.\)
For any system having more than one solution, choose different values of the parameters in the element form of the solution set to find three distinct linear combinations of the columns of \(\A\) which are equal to \(\b.\)
1.
\(\A=\left(\begin{array}{rrr}-1\amp 3\amp 0\\6\amp 2\amp 7 \end{array} \right),\quad\b=\left(\begin{array}{r}1\\3 \end{array} \right)\)
2.
\(\A=\left(\begin{array}{rrrr}1\amp -2\amp 4\amp -2\\1\amp 1\amp -3\amp 5\\0\amp 3\amp -7\amp 7 \end{array} \right),\quad\b=\left(\begin{array}{r}-4\\5\\9 \end{array} \right)\)
3.
\(\A=\left(\begin{array}{rrr}1\amp 10\amp -1\\2\amp 3\amp 5\\-4\amp 11\amp 7 \end{array} \right),\quad\b=\left(\begin{array}{r}-11\\-30\\-76 \end{array} \right)\)
4.
\(\A=\left(\begin{array}{rrrr}1\amp 10\amp -1\amp -3\\2\amp 20\amp 4\amp -3\\1\amp 10\amp 11\amp -6 \end{array} \right),\quad\b=\left(\begin{array}{r}5\\7\\16 \end{array} \right)\)
5.
\(\A=\left(\begin{array}{rr}1\amp -2\\1\amp 5\\-4\amp 6 \end{array} \right),\quad\b=\left(\begin{array}{r}7\\-7\\19 \end{array} \right)\)
6.
\(\A=\left(\begin{array}{rrrr}1\amp 10\amp -1\amp -3\\2\amp 20\amp 4\amp -3\\1\amp 10\amp 11\amp -6 \end{array} \right),\quad\b=\left(\begin{array}{r}5\\7\\17 \end{array} \right)\)
7.
\(\A=\left(\begin{array}{rrr}1\amp 4\amp -3\\2\amp -3\amp 5\\3\amp -5\amp 8\\1\amp 0\amp 3 \end{array} \right),\quad\b=\left(\begin{array}{r}12\\-9\\-15\\5 \end{array} \right)\)
8.
\(\A=\left(\begin{array}{r}3\\1\\5\\15 \end{array} \right),\quad\b=\left(\begin{array}{r}2\\1\\5\\15 \end{array} \right)\)
9.
\(\A=\left(\begin{array}{rrrr}2\amp 15\amp 6\amp 10 \end{array} \right),\quad\b=(30)=30\)
10.
\(\A=\left(\begin{array}{rrrr}3\amp 1\amp 5\amp 15 \end{array} \right),\quad\b=(30)=30\)
11.
\(\A=\left(\begin{array}{rrr}9\amp 3\amp 1\\4\amp 2\amp 1\\5\amp 1\amp 1 \end{array} \right),\quad\b=\left(\begin{array}{r}3\\5\\1 \end{array} \right)\)
12.
\(\A=\left(\begin{array}{rrr}1\amp 2\amp -1\\1\amp 3\amp 1\\3\amp 8\amp 3 \end{array} \right),\quad\b=\left(\begin{array}{r}4\\-3\\-2 \end{array} \right)\)
13.
\(\A=\left(\begin{array}{rrr}1\amp 2\amp -1\\1\amp 3\amp 1\\3\amp 8\amp 3 \end{array} \right),\quad\b=\left(\begin{array}{r}4\\-3\\-1 \end{array} \right)\)