Let A$=[1311]$

$,$ B$=[330112]$

$,$ C$=011213$

and D$=[21]$

$.$

Consider the following expressions:

AB

AC

BTC

A$+$D

B$+$CT

CD

a$)$ Which of these expressions are defined? Enter the corresponding numbers as a list, separated by semi$-$colons $($;$).$

Answer:

$2$;$5$

Pr$$visualiser

b$)$ For which of these formulas is the answer a $2\backslash$times $3$

matrix? Enter the corresponding numbers as a list, separated by semi$-$colons $($;$).$

Answer:

Pr$$visualiser

c$)$ What is the $(2,1)$

entry of the product BC

$?$

Answer:

Nombre

d$)$ What is the $(2,1)$

entry of the product CB

$?$

Answer:

Nombre