## Calcmathlete 3 years ago Matrix Help!

1. Calcmathlete

2. agentc0re

what type of math class is this?

3. Calcmathlete

It's math team :) But it is Algebra II

4. angela210793

I guess this is what you wanted :) |dw:1343828412416:dw|

5. Calcmathlete

Wait, what? o.O I understand what you did when you did the cofactor part, but not after that.

6. angela210793

tell me on my drawing wht didnt u understand please

7. Calcmathlete

|dw:1343828609211:dw| Also, that wasn't the answer they gave?

8. Calcmathlete

Or was that just a part of the process?

9. angela210793

just calculations O.o|dw:1343828726092:dw|

10. Calcmathlete

How does that work? o.O Sorry, I just haven't done TOO much with matrices yet...

11. angela210793

Hmmmm....im sorry i am not sure how to explain you why it is like that....:( it just is like that hmmmm....u can try these...they r pretty good http://www.khanacademy.org/math/algebra/algebra-matrices?k

12. Calcmathlete

Well, the final answer is a matrix...can you tell me what topic for matrices to watch? I've watched all of them to the extent of Algebra II material.

13. angela210793

Hmmmm....maybe I've misunderstood wht u want to find... hang on a sec

14. angela210793

watch inverting matrices

15. Calcmathlete

Wouldn't the inverse be $\left[\begin{matrix}-2 & 1 \\ 4 & 4\end{matrix}\right]$

16. Calcmathlete

Or do I multiply by the reciprocal of the determinant?

17. angela210793

tell me smth u want to find the inverse of the |dw:1343829407799:dw|

18. Calcmathlete

Would I perform this: $-\frac1{12}\left[\begin{matrix}-2 & 1 \\ 4 & 4\end{matrix}\right]$

19. Calcmathlete

Yes. I want to find the inverse of what's above in your picture.

20. angela210793

learnt this At Khan's videos so jusat plug in the numbers now |dw:1343829481250:dw|

21. angela210793

or read this...is very well explained http://dcann.myweb.uga.edu/lect08add.pdf

22. Calcmathlete

Isn't that what I did above? |dw:1343829681330:dw|

23. angela210793

yup :)

24. Calcmathlete

Alright, so the answer would be: $\left[\begin{matrix}\frac16 & -\frac1{12} \\ -\frac13 & -\frac13\end{matrix}\right]$

25. angela210793

shouldnt it be |dw:1343830119553:dw|

26. Calcmathlete

Is there supposed to an aboslute value on the A? not sure...I thought that a and d switched places and that b and c negated...maybe I'm wrong?

27. angela210793

no abs value

28. Calcmathlete

So it would be correct what I did?

29. angela210793

hang on a sec pls...im on the phone

30. angela210793

i said so...from the second link i sent u

31. Calcmathlete

Wait. Let me check the link...

32. angela210793

oh wait ...-_-

33. Calcmathlete

I have not gone that far into matrices quite yet...haven't learned to transpose... -_-

34. angela210793

it was as u said...sorry...it's too hot in here -_-'' I'm not thinking well :p |dw:1343830633083:dw|

35. Calcmathlete

lol ok. Thanks :)

36. angela210793

|dw:1343830704511:dw|