## Imtiaz7 one year ago Help Please...!

1. Imtiaz7

Reduce following matrix into Reduce Echlon Form:|dw:1439303190612:dw|

2. Imtiaz7

@UsukiDoll

3. anonymous

@pooja195

4. anonymous

Oooh... the matrix :>

5. anonymous

$\Large \left[\begin{matrix}1&-1&2&1\\5&0&4&2\\4&1&2&0\\1&1&1&1\end{matrix}\right|\left.\begin{matrix}1\\3\\1\\0\end{matrix}\right]$

6. anonymous

I'm awesome :)

7. anonymous

What did you try?

8. anonymous

@Imtiaz7

9. Imtiaz7

I try but couldnt get right answer

10. anonymous

That's because you don't use magic :D

11. Imtiaz7

will you teach me magic :D

12. anonymous

Well, let's see now: Add the first row to the third $\Large \left[\begin{matrix}1&-1&2&1\\5&0&4&2\\5&0&4&1\\1&1&1&1\end{matrix}\right|\left.\begin{matrix}1\\3\\2\\0\end{matrix}\right]$

13. anonymous

Any suggestions from you?

14. Imtiaz7

Can you tell me why?

15. anonymous

Well, look what happened? It looks nice :D You can easily subtract the second row from the third, and get something simple... $\Large \left[\begin{matrix}1&-1&2&1\\5&0&4&2\\0&0&0&-1\\1&1&1&1\end{matrix}\right|\left.\begin{matrix}1\\3\\-1\\0\end{matrix}\right]$

16. Imtiaz7

how the first element of third row becomes zero

17. anonymous

Subtracted the second row from the third? 5 - 5 = 0

18. Imtiaz7

Okay

19. anonymous

We can add the third row to the first and fourth row to get $\Large \left[\begin{matrix}1&-1&2&0\\5&0&4&2\\0&0&0&-1\\1&1&1&0\end{matrix}\right|\left.\begin{matrix}0\\3\\-1\\-1\end{matrix}\right]$

20. Imtiaz7

ok..

21. anonymous

Also add twice the third row to the second row $\Large \left[\begin{matrix}1&-1&2&0\\5&0&4&0\\0&0&0&-1\\1&1&1&0\end{matrix}\right|\left.\begin{matrix}0\\1\\-1\\-1\end{matrix}\right]$ Maybe you should work out the rest. It's much simpler now ^.^

22. Imtiaz7

okay thnaks :)