Matrix Basix Examples

Find 3X – Y.

We need to scalar multiply X by 3, then subtract Y.

Find Y^T.

Remember the transpose is just flipping the rows and columns.

Did you notice that the main diagonal stayed the same?

Using a calculator, find the determinant for X.

Technology Alert

Here are the instructions for finding the determinant of this matrix on the TI-84 Plus calculator:

• 2nd MATRIX (which is the X^-1 button), arrow twice right to the EDIT, Enter on A
• Type the row and column dimension (3 × 3) and press Enter
• Type in the matrix
• 2nd QUIT to get back out to the main menu
• 2nd MATRIX, arrow right once to MATH
• Press Enter on the 1:det(
• 2nd MATRIX, hit Enter on 1:[A]
• Hit Enter one more time and...you should get -166
• Drive to Walmart, hold your calculator in the air while you run around the store yelling "I found the inverse! I found the inverse!"

Using a calculator, find the inverse for X.

If you forgot about this (and it's okay if you did), refer back to the instructions earlier in the section for using the TI-84 Plus to find the inverse.