Question

find solutions to the following using Excel's matrix operations?

Answer 1

Finding a matrix product AB
Suppose you want to find the product AB. You will first need to determine the order of the resulting matrix.
Suppose A is an n × m matrix and B is an m × p matrix. The order of AB is then n × p.
To find AB in Excel, simply enter the numbers in the matrices anywhere on your spreadsheet. Perform the
following steps:
• Select an empty n × p block of cells in your spreadsheet(if you know your matrix product is an n × p
matrix).
• Press the “F2” key.
• Press the “=” sign.
• Type in “MMULT(”.
• Select the cells containing A and enter a comma (,).
• Select the cells containing B.
• Close the bracket “)”.
• Hold down the keys “Ctrl” and “Shift” at the same time and press the “Enter” key while holding
down the other two.

Finding A−1
Enter the numbers in A in any 3 × 3 cell block in Excel, putting each number in its own cell, in the rows and
columns as they appear in A. (If your matrix is an n × n matrix, use an n × n cell block.
Since A−1 is a 3 × 3 matrix, select a 3 × 3 cell block anywhere else in your spreadsheet.
Perform the following steps (in the order given):
• Press the “F2” key.
• Press the “=” sign.
• Type in “MINVERSE(”.
• Select the cells containing A−1.
• Close the bracket “)”. You should now have something that looks like the screen shot shown on the left
below.
• Hold down the keys “Ctrl” and “Shift” at the same time and press the “Enter” key while holding
down the other two.
A−1 should now appear in the block of cells you had selected.