Question

Can anyone take me through a matrices question step by step? Please(:

Answer 1

maybe ... whats the question?

Answer 2

if tis QR decomp im a bit rusty

Answer 3

Find -5A + 4B

Answer 4

Do you know that?

Answer 5

oh, something rather basic ... so whats giving you the issue?

Answer 6

yeah .... its just multiplication and addition

Answer 7

multiply all of the elements in A by -5, and all the elements in B by 4

then add them together by like 'components'

Answer 8

everything lol Idk where to start

Answer 9

start with ...

multiply all of the elements in A by -5

then move on to multiplying all the elements in B by 4

end by adding the results by like components

Answer 10

6*(-5) = -30
1(-5) = -5
-4(-5) = 20
-6(-5) = 30
7(-5) =-35
-7(-5) = 35
b.

-5(4) = -20
-1(4) = -4
-3(4) = -12
-8(4) = -32
6(4) = 24
8(4) = 32

Answer 11

Like that?

Answer 12

that looks good so far :)

Answer 13

I add it now?

Answer 14

thats perfect, and a nice format really

now add the first of A with the first of B
then the second of A with the second of B
and all the way to the end

Answer 15

Thanks, (:

& bear with me im kinda slow lol

Answer 16

6(-5) = -30
-5(4) = -20: -50

1(-5) = -5
-1(4) = -4: -9

-4(-5) = 20
-3(4) = -12: 8

-6(-5) = 30
-8(4) = -32: -2

7(-5) =-35
6(4) = 24: -11

-7(-5) = 35
8(4) = 32: 67

Answer 17

youre doing fine :)

Answer 18

thanks for making it easier

50 + -9= 41
8 + -2 = 6
-11 + 67 = 56

Answer 19

you only need to do the addition once ... the matrix solution will simply be

\[-5A + 4B = \begin{vmatrix} -50 & -9\\

8 & -2\\

-11& 67\\
\end{vmatrix}\]

Answer 20

Oh isee my bad, what do I do next?

Answer 21

Oh wait thats it right?