Pearson Algebra 2 Common Core, 2011
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Pearson Algebra 2 Common Core, 2011 View details
6. Solving Systems Using Matrices
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Exercise 39 Page 180

Begin by writing the given system as a matrix and then solve it using row operations.

(2,3)

Practice makes perfect

Let's begin by writing the given system as a matrix.

Matrix

To rewrite the system of equations as a matrix, we need to consider how the elements of the system relate to the elements of a matrix.

  • The equals signs in the system of equations are represented with a vertical bar in the matrix.
  • The coefficients of the variables form the columns on the left-hand side of the bar.
  • The constants form the column on the right-hand side of the bar.
Below we demonstrate this in a generalized form.

a_(11)x+ a_(12)y=c_1 a_(21)x+ a_(22)y=c_2 ⇕ [ cc|c a_(11) & a_(12) & c_1 a_(21) & a_(22) & c_2 ] When each equation in the system is written in the same order, we can consider the coefficients of the variables and the constants. 2x+ 3y=13 5x+ 7y=31 Now that we have identified all of the variables and constants, we can place them in a matrix. [ cc|c 2 & 3 & 13 5 & 7 & 31 ]

Solving the Matrix

In order to solve the matrix, we will use row operations to obtain a matrix in the following form. [ cc|c 1 & 0 & a 0 & 1 & b ] This final matrix represents the solution of the system of equations, where x= a and y= b. Let's solve the matrix!
[ cc|c2 & 3 & 13 5 & 7 & 31 ]
[ cc|c10 & 15 & 65 5 & 7 & 31 ]
[ cc|c10 & 15 & 65 10 & 14 & 62 ]
[ cc|c10 & 15 & 65 10- 10 & 14- 15 & 62- 65 ]
[ cc|c10 & 15 & 65 0 & -1 & -3 ]
[ cc|c10 & 15 & 65 0 & 15 & 45 ]
[ cc|c10- 0 & 15- 15 & 65- 45 0 & 15 & 45 ]
[ cc|c10 & 0 & 20 0 & 15 & 45 ]
[ cc|c1 & 0 & 2 0 & 15 & 45 ]
[ cc|c1 & 0 & 2 0 & 1 & 3 ]
The solution is the point (2,3).