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PRESENTS

THE MATRICES

MATRICES Review

ORDER ?

One way that some people remember that the notation for matrix dimensions is rows by columns

(Rather than columns by rows) is by recalling a once popular-soda:

RC Cola -- rows before columns!

rows and columns of a given matrix

The order of a matrix refer to the number of

By convention the order of a matrix is given by number of rows x number of column

(2 x 3)

Elements of a Matrix In order to identify an element in a matrix,

we simply write a subscript of the respective entry's row followed by the column

Multiplication of MatricesYou can multiply two matrices if, and only if, the number of columns in the first matrix equals the number of rows in the second matrix. Otherwise, the product of two matrices is undefined .

For example if matrix A has the order 5 x 4 and matrix B has the order 4 x 1, then the resulting matrix C would have the order 5 x 1 when both matrices are multiplied

The product matrix's order are (rows of first matrix) × (columns of the second matrix )

Matrix C and D below cannot be multiplied together because the number of columns in C does not equal the number of rows in D. In this case, the multiplication of these two matrices is not defined

Multiplication of MatricesVideo

Steps in Multiplication of 2 Matrices

Step 1: Make sure that the the number of columns in the 1st matrix equals the number of rows in the 2nd matrix. (The pre-requisite to be able to multiply)

Step 2: Multiply the elements of each row of the first matrix by the elements of each column in the second matrix.

Step 3: Add the products.

Exercises