Adding, Subtracting and Multiplying Matrices

What are the dimensions of this matrix?

• 2 x 3

• 3 x 2

• 6 x 1

• 1 x 6

Find A+B

• 8     10
  8      1 

• 12     25
  7     1

• 10     30
  0     1

• can't add two together because the rows dont match columns

• 2

• 7

• 4

• -3

Which sums can NOT be made from the following matrices ?

• A+A

• A+C

• B+D

• C+C

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Find the values of w, x, y and z.

• 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

What is a₂₃

• 14

• 4

• 1

• 3

If A is a 2 × 3 matrix, and B is a 3 × 4 matrix, how many columns does AB have?

• 2

• 3

• 4

• AB is not defined

Matrices can be multiplied only...

• if the row of the first matrix is equal to the column of the second matrix.

• if the column of the first matrix is equal to the column of the second matrix.

• if the column of the first matrix is equal to the row of the second matrix.

• if the row of the first matrix is equal to the row of the second matrix.

The matrix A - B is

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