In-Class Work, Tuesday September 19
Math 221 Linear Algebra
September 19, 2023

T. Ratliff, Wheaton College
ratliff_thomas@wheatoncollege.edu

Matrices used for Problems 1 - 4

I’ll use lower-case letters to keep from conflicting with any Mathematica commands.

a = {{1,2},{3,4}}
b={{4,0},{3,4}}
c={{2,-4},{3,-6}}
d={{1,2,-3},{-2,1,3}}

The syntax to multiply matrices a and b in Mathematica is a.b

a.b

Or prettied up

a.b //MatrixForm

Mathematica can also compute inverses and transposes, and we can combine these if we want (although I’m not sure why you’d want to compute (a (((b^(-1))))^T) ).

Inverse[a] //MatrixForm

Transpose[a] //MatrixForm

Transpose[a.Inverse[b]] //MatrixForm

Matrices used for Problems 5 - 9

As above, I’ll use lower case letters so that it doesn’t conflict with any built in Mathematica commands.

f={{1,0,3},{2,2,3},{0,4,-7}}
g={{3,-2,4},{7,12,8},{16,2,3}}
e1 = {{1,0,0},{-2,1,0},{0,0,1}}
e2={{1,0,0},{0,1/2,0},{0,0,1}}