Chapter 16.9, Problem 15OE

To determine

To calculate: The entries of the determinant $D_y$ for the system of equations,

  $\begin{array}{c}5x-y=-17\\ -2x+3y+3z=12\\ z=0\end{array}$

Answer to Problem 15OE

The column one of determinant $D_y$ is $\left[\begin{array}{c}5\\ -2\\ 0\end{array}\right]$ , column two is $\left[\begin{array}{c}-17\\ 12\\ 0\end{array}\right]$ and column three is $\left[\begin{array}{c}0\\ 3\\ 1\end{array}\right]$ .

Explanation of Solution

Given information:

The system of equations are

  $\begin{array}{c}5x-y=-17\\ -2x+3y+3z=12\\ z=0\end{array}$

Formula used:

For system of equations

  $\begin{array}{c}{a}_{1}x+b_{1}y+c_{1}z=d_1\\ a_{2}x+b_{2}y+c_{2}z=d_2\\ a_{3}x+b_{3}y+c_{3}z=d_3\end{array}$

The determinant $D_y$ is the coefficients of the variables x and z along with constant term in column form,

  $D_y=\left|\begin{array}{ccc}{a}_1& d_1& c_1\\ a_2& d_2& c_2\\ a_3& d_3& c_3\end{array}\right|$

Calculation:

Consider the system of equations are

  $\begin{array}{c}5x-y=-17\\ -2x+3y+3z=12\\ z=0\end{array}$

Recall that for system of equations

  $\begin{array}{c}{a}_{1}x+b_{1}y+c_{1}z=d_1\\ a_{2}x+b_{2}y+c_{2}z=d_2\\ a_{3}x+b_{3}y+c_{3}z=d_3\end{array}$

The determinant $D_y$ is the coefficients of the variables x and z along with constant term in column form,

  $D_y=\left|\begin{array}{ccc}{a}_1& d_1& c_1\\ a_2& d_2& c_2\\ a_3& d_3& c_3\end{array}\right|$

Column one of determinant has coefficients of x in all three equations.

Column two of determinant has constant term of all three equations.

Column three of determinant has coefficients of z in all three equations.

  $D_y=\left|\begin{array}{ccc}5& -17& 0\\ -2& 12& 3\\ 0& 0& 1\end{array}\right|$

Thus, the column one of determinant is $\left[\begin{array}{c}5\\ -2\\ 0\end{array}\right]$ , column two is $\left[\begin{array}{c}-17\\ 12\\ 0\end{array}\right]$ and column three is $\left[\begin{array}{c}0\\ 3\\ 1\end{array}\right]$ .