As you may have noticed, some matrix operations are very tedious by hand. In particular, matrix multiplication and matrix inverses are much easier to do using a graphing calculator or WolframAlpha. In the Weekly Learning Plan, I put several handouts to help you use your calculator to do these problems.
- Handout: Matrix Multiplication on a TI Graphing Calculator
- Handout: Inverse Matrix on a TI Graphing Calculator
- Handout: Solve a System with Inverses on a TI Graphing Calculator
However, some of you do not have a graphing calculator…you’ll need to use WolframAlpha to carry out these operations.
Suppose you want to find the inverse of
To do this, you need to type inverse of and then put the matrix in using curly braces.
Notice that each row of the matrix needs to be in braces as well as the matrix itself.
The inverse of
is carried out in a similar manner:
You can also do the inverse by entering the matrix followed by ^-1:
Either way, you get the same answer.
Suppose you want to multiply two matrices like
All you need to do is enter each matrix side by side:
WolframAlpha will assume that you want multiplication and do the math for you. If you put + or – between the matrices, you can have WolframAlpha add or subtract the matrices too.