## anonymous one year ago I am confused on how to go about doing this. Linear algebra question for homework

1. anonymous

2. misty1212

HI!!

3. anonymous

Hello

4. misty1212

one way to do it would be to multiply the matrix on the right by the inverse of the matrix on the left

5. misty1212

$AB=C\iff A=CB^{-1}$

6. anonymous

oh ok

7. anonymous

let me try that i'll respond once I have done that

8. misty1212

inverse of a 2 by 2 matrix is easy to find right?

9. anonymous

yes

10. misty1212

$\begin{pmatrix} x & y \\ z & v \end{pmatrix}^{-1}=\frac{1}{D}\begin{pmatrix} v & -y \\ -z & x \end{pmatrix}$

11. misty1212

course you can always cheat too, not really necessary

12. misty1212
13. anonymous

so the inverse would be $\left[\begin{matrix}2.5 & -2 \\ -0.5 & 0.5\end{matrix}\right]$ right?

14. anonymous

or have i done it wrong?

15. misty1212

looks good

16. misty1212

oh no

17. misty1212

the -5 is wrong

18. misty1212

that should be -1

19. anonymous

-5?

20. misty1212

first get $\begin{pmatrix} 5& -4 \\ -2 & 2 \end{pmatrix}$

21. misty1212

the divide all by 2

22. anonymous

oh wait i know what u mean lol, that was my mistake

23. anonymous

i thought the 2 were 1s

24. anonymous

lol

25. misty1212

$\begin{pmatrix} 2.5& -2 \\ -1 & 1 \end{pmatrix}$

26. misty1212

i think that is right

27. anonymous

yes, that is, so now I just have to multiply that by the resultant in the question correct?

28. misty1212
29. anonymous

ok, ill do it, and see if i got that on paper

30. misty1212

ok good luck!$\color\magenta\heartsuit$

31. anonymous

yup i got the same answer, Thank you so much for your help. :D