Solving in Matrices

Find 2A-3B

• -3 1

  7 -1

• 1 0

  1 -4

• -4 0

  6 -1

• -14 -5

  11 -3

Find A-B

• -3     1
  7     -1

• 1     0
  1     -4

• -4       0
  6     -1

• not possible because rows do not match columns

What do m, n, p and q equal in this scalar matrix multiplication?

• m=8, n=9, p=-4, q=4 

• m=15, n = -45, p=20, q=-5

• m=20, n=-5, p=15, q=-45

• m=-5, n=20, p=-45, q=15

To add or subtract matrices, which of the following must be true?

• They are the same matrix

• They have the same dimensions

• Rows in the 1st matrix must have the same # of terms as the columns as the 2nd matrix

• All matrices can be added

What do w, x, y and z equal in this matrix equation?

• w = 13, x = 4, y = 7, z = 23

• w = 13, x = -4, y = 11, z = 23

• w = 13, x = 4, y = 11, z = 23

• w = 13, x = 4, y = 11, z = 17

Find 2B-5A

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• 
• 
• 

Find 3B - 2A

• [22 25]

  [17 3]

• [14 5]

  [-11 3]

• [-14 5]

  [11 -3]

• none of these

Solve the system.  Write the matrix equation on your own paper.
-5x + 5y = -10
-7x + 4y = 13

• (-7, -5)

• (-7, -9)

• (7, -9)

• (-7, 5)

• 
• 
• 
• 

Solve the system.  Write the matrix equation on your own paper.
5x + 8y = -12
3x + 5y = -7

• (1, -10)

• No solution

• (-4, 1)

• (1, 10)