Chapter 8: Problem 76
Determine whether the statement is true or false. Justify your answer. Matrix multiplication is commutative.
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Chapter 8: Problem 76
Determine whether the statement is true or false. Justify your answer. Matrix multiplication is commutative.
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Using a Graphing Utility, use the matrix capabilities of a graphing utility to write the augmented matrix corresponding to the system of equations in reduced row-echelon form. Then solve the system. $$\left\\{\begin{aligned} 3 x+3 y+12 z &=6 \\ x+y+4 z &=2 \\ 2 x+5 y+20 z &=10 \\\\-x+2 y+8 z &=4 \end{aligned}\right.$$
Properties of Determinants In Exercises \(101-103\) ,a property of determinants is given \((A\) and \(B\) are squarematrices). State how the property has been applied to the given determinants and use a graphing utility to verify the results. Properties of Determinants In Exercises \(101-103\) ,a property of determinants is given \((A\) and \(B\) are squarematrices). State how the property has been applied to the given determinants and use a graphing utility to verify the results. If \(B\) is obtained from \(A\) by interchanging two rows of \(A\) or interchanging two columns of \(A,\) then \(|B|=-|A|\) $$(a)\left| \begin{array}{rrr}{1} & {3} & {4} \\ {-7} & {2} & {-5} \\ {6} & {1} & {2}\end{array}\right|=-\left| \begin{array}{rrr}{1} & {4} & {3} \\ {-7} & {-5} & {2} \\ {6} & {2} & {1}\end{array}\right|$$ $$(b)\left| \begin{array}{r|rrr}{1} & {3} & {4} \\ {-2} & {2} & {0} \\ {1} & {6} & {2}\end{array}\right|=-\left| \begin{array}{rrr}{1} & {6} & {2} \\ {-2} & {2} & {0} \\ {1} & {3} & {4}\end{array}\right|$$
Elementary Row Operations, fill in the blank(s) using elementary row operations to form a row-equivalent matrix. $$\left[ \begin{array}{rrr}{-3} & {3} & {12} \\ {18} & {-8} & {4}\end{array}\right]$$ $$\left[ \begin{array}{rrr}{1} & {-1} & {} \\ {18} & {-8} & {4}\end{array}\right]$$
Conjecture Consider square matrices in which thh entries are consecutive integers. An example of such a matrix is $$\left[ \begin{array}{rrr}{4} & {5} & {6} \\ {7} & {8} & {9} \\ {10} & {11} & {12}\end{array}\right]$$ (a) Use a graphing utility to evaluate the determinants of four matrices of this type. Make a conjecturebased on the results. (b) Verify your conjecture.
Comparing Linear Systems and Matrix Operations In Exercises 41 and \(42,\) (a) perform the row operations to solve the augmented matrix, (b) write and solve the system of linear equations represented by the augmented matrix, and (c) compare the two solution methods. Which do you prefer? $$\left[ \begin{array}{rrrr}{-3} & {4} & {\vdots} & {22} \\ {6} & {-4} & {\vdots} & {-28}\end{array}\right]$$ $$\begin{array}{l}{\text { (i) Add } R_{2} \text { to } R_{1} \text { . }} \\\ {\text { (ii) Add }-2 \text { times } R_{1} \text { to } R_{2} \text { . }} \\\ {\text { (iii) Multiply } R_{2} \text { by }-\frac{1}{4}} \\ {\text { (iv) Multiply } R_{1} \text { by } \frac{1}{3}}\end{array}$$
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