Lesson 2: Multiplying Matrices Accel Precalc Unit 3: Matrices Lesson 2: Multiplying Matrices EQ: How do you multiply matrices?

Condition Necessary to Multiply two Matrices: Since each matrix represents an array of data, rules for multiplying them together depends on the position of each entry. Condition Necessary to Multiply two Matrices: # of columns of 1st matrix = # of rows of 2nd matrix

AB will result in a 3 x 2 matrix. Given matrix A and matrix B with the following dimensions: AB will result in a 3 x 2 matrix.

Ex. 1 Matrix D is a __ by __. Matrix A is a __ by __. 2 3 3 2 2 x 3 3 x 2 Therefore the product WILL exist. It will be a ___ by ___ matrix. 2 2

Product will be a ____ x ____ matrix. Process to Multiply Matrices: 2 x 2 2 x 2 Product will be a ____ x ____ matrix. 2 2 AB =

AB =

Ex. 2 Find the product given   a) JK b) KJ

Ex. 3 Find the product given a) RW b) WR

Ex. 4 Find each product given BA b) (CB)A

ASSIGNMENT: Textbook p. 577 – 578 #3, 7, 17, 33 – 35, 39