Question

a) Find the product of the 2 matrices below showing all your working.

[2 7] [3 8]
[-1 4] [5 0]

b) Find the product of the 2 matrices below showing all your working and explain the significance of this result.

[3 8] [2 7]
[5 0] [-1 4]

If A= [7 8]
[5 2] Find A^-1

Answer 1

hm.. how to do this one..?

Answer 2

i believe its...

2.3+7.5 2.8+7.0

-1.3+4.5 -1.8+4.0

Answer 3

hm.. I don't know whether it's right or wrong..

Answer 4

its right for a

Answer 5

2.3 means 2(3)... just in a lazy format

Answer 6

its like this:
(2x3)+(7x5) (8x2)+(7x0)
(-1x3)+(4x5) (-1x8)+(4x0)

Answer 7

6+35 = 41 16+0 = 16
-3+20=17 -8+0=-8

Answer 8

Yup, I got the answer for a.. but, I'm stuck in b and c...

Answer 9

do the same process in b

Answer 10

yep

Answer 11

how to explain the significance of this result??

Answer 12

b is the same process:

[3 8] [2 7]
[5 0] [-1 4]

3.2+8.-1 = -2 3.7+8.4= 53
5.2+0.-1= 10 5.7+0.4=35

Answer 13

c; find the inverse...

[7 8] 7.a+8.c=1 7.b+8.d=0
[5 2] 5.a+2.c=0 5.b+2.d=1

Answer 14

in part c its doing the nverse, do you know the proces of doing it?

Answer 15

[a b]
[c d] will be the inverse

Answer 16

the short cut is to flip and negate the 7 and 2 :)

Answer 17

it is the 7 and 2 right?

Answer 18

flip a d and negate b c

Answer 19

[2 -8]
[-5 7]

Answer 20

ok I've flipped a d and negate b c..

Answer 21

that is the inverse of A :)

Answer 22

ok thank you..! So after inverse, there's nothing else right?

Answer 23

yup amistre got it,, theres nothing else

Answer 24

Thanks so much guys!

Answer 25

wc