Let upper a equals left bracket start 2 by 2 matrix 1st row 1st column negative 2 2nd column 4 2nd row 1st column 1 2nd column 3 endmatrix right bracketa=

−2 4
1 3
, and upper b equals left bracket start 2 by 2 matrix 1st row 1st column negative 2 2nd column 1 2nd row 1st column 3 2nd column 7 endmatrix right bracketb=

−2 1
3 7
.a. find

abab,

if possible. b. find

baba,

if possible.

c. are the answers in parts a and b the same?

d. in general, for matrices a and b such that ab and ba both exist, does ab always equal ba?

a. find

abab,

if possible.