## anonymous 4 years ago Evaluate C - D. (Image attached.)

1. jhonyy9

???

2. anonymous

3. anonymous

Exactly the same just subtract...?

4. anonymous

I don't even understand how to do it though..

5. ash2326

$\left[\begin{matrix}a & b \\c& d\end{matrix}\right]-\left[\begin{matrix}e & f \\g& h\end{matrix}\right]=\left[\begin{matrix}a-e & b-f \\c-g& d-h\end{matrix}\right]$

6. anonymous

Those are just the variables ash2326

7. ash2326

Kaup Kel use this to evaluate the matrix subtraction, Did you get it?

8. anonymous

I really really just need to learn from scratch how to do this. I don't even know what matrix is....

9. ash2326

I'll show you $\left[\begin{matrix}7 & 11 \\-15& 3\end{matrix}\right]-\left[\begin{matrix}1 & 0 \\4& \frac{-11}{2}\end{matrix}\right]=\left[\begin{matrix}(7-1) & (11-0) \\(-15-4)& (3- \frac{-11}{2})\end{matrix}\right]$

10. ash2326

Kaupkel did you understand this??

11. anonymous

Not at all, but that's okay. You tried to help me, and I appreciate it. I just don't know what I'm going to do. This is all new to me.

12. ash2326

Let me give you an idea of matrix

13. anonymous

Okay.

14. ash2326

Matrix is a rectangular array of numbers or variables . The numbers are called elements of matrix. See this is a matrix with 4 elements a, b, c, d $\left[\begin{matrix}a & b \\c& d\end{matrix}\right]$

15. ash2326

Did you get this?

16. anonymous

Yes.. so far(:

17. ash2326

|dw:1328646952010:dw|Now matrix has rows and columns, in the example I showed you, it has 2 rows and 2 columns.

18. ash2326

Got this?

19. ash2326

we can have any number of rows or columns, may or may not be equal

20. anonymous

Okay.. I'm understanding you so far..

21. ash2326

Now last thing for today , matrix when added or subtracted the individual elements are added or subtracted. But remember one thing

22. anonymous

But wait! How do I solve one though. That's what I wanted to know the most.

23. ash2326

The matrices being added should have equal no. of rows and columns. In our example both the matrices have equal no. of rows and columns 2 *2

24. ash2326

Kaupkel, your question has two matrices , both are 2*2, so subtract corresponding elements for example 7-1=6

25. ash2326

and do this for remaining 3 and place the result at the respective position, see the post where I'd solved this one above

26. ash2326

Kaupkel got it?

27. anonymous

Kind of, except what is a corresponding element?

28. ash2326

|dw:1328647944077:dw|These are corresponding elements

29. ash2326

11 and 0 are also corresponding elements

30. ash2326

|dw:1328648206940:dw|

31. anonymous

Thank you for all your time and effort. I kind of understand it now. Can you solve the question I put? I think it would help me understand better, since it's an actual full question..

32. ash2326

I have solved it, see above

33. anonymous

Thanks! I totally understand it now! I'm so excited.. but what about the 4th corresponding element? Did you forget to do it, or did you want me to figure it out?

34. ash2326

Actually I didn't have space for that, you tell what will be the 4th element?

35. anonymous

I'm not real sure what will be the 4th element since it's like a fraction.

36. ash2326

3-(-11/2) 3+11/2 6/2+11/2=17/2

37. anonymous

so 17/2 is the fourth element?

38. ash2326

Yeah kaupkel

39. ash2326

got it now?

40. anonymous

Yes I do! But are you supposed to solve the elements in the answer in the most recent drawing you did?

41. ash2326

yeah , like that and you have to write like that only

42. anonymous

Oh. Okay! I'm so excited that I understand this! Haha. Thank you again for all your help. Sorry for taking up so much of your time too. Lol.

43. anonymous

So just to be sure, It would be wrtitten like this right? 6 11 -19 17/2

44. ash2326

Yeah Kaupkel, it's written like that. Don't be sorry , I'm glad to help :)

45. anonymous

Thank you so much!! You are like the awesomest person ever! and the first to actually take time to help me on here...

46. ash2326

You'd find more people like me here. It's great that I could help. Do try more problems, you'll learn more. :):)

47. anonymous

Okay! Thanks!!

48. anonymous

One more thing I need help with, if you don't mind...

49. ash2326

Yeah :)

50. anonymous

Thank you! And I just came accross a question on my homework that is exactly what we just did except there's 3 rows of elements.. I'm not real sure how to find the corresponding elements for those.

51. ash2326

subtract element by element, doesn't matter how many rows are there see|dw:1328650357384:dw|

52. anonymous

Yeah, but I don't know which ones to match up with which. You know?

53. ash2326

see Ist row, 1st column matches to 1st row, 1st column of other matrix similarly just add or subtract the elements with same row no. and column no. check this link also http://en.wikipedia.org/wiki/Matrix_addition

54. anonymous

So, tell me if I got this right...... 14 6 19 18 11 9 I'll post the problem with it in a sec.

55. anonymous