Chapter 6: Problem 53
Explain how to evaluate a third-order determinant.
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Chapter 6: Problem 53
Explain how to evaluate a third-order determinant.
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Consider the system $$ \begin{array}{l}a_{1} x+b_{1} y=c_{1} \\\a_{2} x+b_{2} y=c_{2}\end{array} $$ Use Cramer's rule to prove that if the first equation of the system is replaced by the sum of the two equations, the resulting system has the same solution as the original system.
In Exercises \(27-36,\) find (if possible): \(\begin{array}{llll}\text { a. } A B & \text { and } & \text { b. } B A\end{array}\) $$ A=\left[\begin{array}{rrrr} 2 & -3 & 1 & -1 \\ 1 & 1 & -2 & 1 \end{array}\right], \quad B=\left[\begin{array}{rr} 1 & 2 \\ -1 & 1 \\ 5 & 4 \\ 10 & 5 \end{array}\right] $$
Use Cramer's rule to solve each system or to determine that the system is inconsistent or contains dependent equations. $$ \begin{aligned}&4 y=16-3 x\\\&6 x=32-8 y\end{aligned} $$
If two matrices can be multiplied, describe how to determine the order of the product.
Determinants are used to find the area of a triangle whose vertices are given by three points in a rectangular coordinate system. The area of a triangle with vertices\(\left(x_{1}, y_{1}\right),\left(x_{2}, y_{2}\right),\) and \(\left(x_{3}, y_{3}\right)\) is $$ \text { Area }=\pm \frac{1}{2}\left|\begin{array}{lll}x_{1} & y_{1} & 1 \\\x_{2} & y_{2} & 1 \\\x_{3} & y_{3} & 1\end{array}\right| $$ where the \(\pm\) symbol indicates that the appropriate sign should be chosen to yield a positive area. Use this information to work. Use determinants to find the area of the triangle whose vertices are \((3,-5),(2,6),\) and \((-3,5)\).
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