Question

Please help me!!! with this ASAP!!
1Given A = [1 -1 2] and B=[-1 -3 2] find AB.
[ 3 0 5 [ 2 4 5]
[0 2 -2]

A. [3 -3 -7 ]
[-3 -1 4]

B. [3 3 5]
[-2 6 4]
[1 10 0]

C. [-3 -3 -7]
[-3 1 -4]

D. [3 -3]
[-3 1]
[-7 -4]

Answer 1

we can eliminate 2 of the options ... what format do you spose the end result will be in?

Answer 2

B is just 3 column vectors ....

Apply each column vector to A, one by one.

Answer 3

so do you like multiply it ?

Answer 4

yes .... if you can recall how to do matrix multiplication

Answer 5

so I got
[ 1 3 4 ]
[ 6 0 25]

how do you do the 3rd one ? and what do you do next

Answer 6

[1/3 -1/0 2/5] [-1/2/0 -3/4/2 2/5/-2]

can be split into 3 parts ...operations

[1/3 -1/0 2/5] [-1/2/0]
[1/3 -1/0 2/5] [-3/4/2]
[1/3 -1/0 2/5] [2/5/-2]

Answer 7

-1 2 0
[1/3 -1/0 2/5]
-----------------
[-1/-3 -2/0 0/0] -> [-3/-3]
add tops/add bottoms


-3 4 2
[ 1/3 -1/0 2/5]
-----------------
[-3/-9 -4/0 4/10] -> [-3/1]



2 5 -2
[ 1/3 -1/0 2/5]
------------------
[2/6 -5/0 -4/-10] -> [-7/-4]


so ....

[-3/-3 -3/1 -7/-4]

Answer 8

oh okay i get it now thank you so very much :)

Answer 9

good luck ... i find that format a good approach for some reason lol. i guess it keeps things in order for me better