# MATRIX problem: Help needed

• Jun 13th 2006, 09:12 PM
lalitchugh
MATRIX problem: Help needed
Hi,

Pls help to pricved solution of the below problem.

Consider the following 3 matrices:

2 12 18
13 15 20
19 17 1

12 2 1
13 14 21
9 18 7

12 2 7
30 18 22
9 16 4

Find --> (inverse of A i.e A-1) x (B x – C)

Please mail me the solution on lalitchugh@yahoo.com

Best Regards
Lalit Chugh
• Jun 14th 2006, 10:49 PM
CaptainBlack
Quote:

Originally Posted by lalitchugh
Hi,

Pls help to pricved solution of the below problem.

Consider the following 3 matrices:

2 12 18
13 15 20
19 17 1

12 2 1
13 14 21
9 18 7

12 2 7
30 18 22
9 16 4

Find --> (inverse of A i.e A-1) x (B x – C)

$A^{-1} B (-C)\approx \left[ \begin{array}{ccc}
-51.6&-54.6&-32.5\\
16.9&35.7&8.2\\
-17.4&-21.9&-9.2
\end{array} \right]
$

Quote:

Please mail me the solution on lalitchugh@yahoo.com

No.

RonL
• Jun 15th 2006, 04:46 AM
topsquark
Quote:

Originally Posted by CaptainBlack
$A^{-1} B (-C)\approx \left[ \begin{array}{ccc}
-51.6&-54.6&-32.5\\
16.9&35.7&8.2\\
-17.4&-21.9&-9.2
\end{array} \right]
$

No.

RonL

Or to be precise:

$\frac{1}{2602} \left [ \begin{array}{ccc}-134355&-142196&-84492\\43995&92792&21298\\-45192&-57048&-23892\end{array} \right ]$

To expand on CaptainBlack's "no," please be aware that it is better for everyone on the site to have the solution posted here so someone else who wants to learn the process can do so and ask questions about it. If the solution is simply sent to your e-mail others will not benefit as well.

-Dan
• Jun 15th 2006, 05:03 AM
CaptainBlack
Quote:

Originally Posted by topsquark
Or to be precise:

$\frac{1}{2602} \left [ \begin{array}{ccc}-134355&-142196&-84492\\43995&92792&21298\\-45192&-57048&-23892\end{array} \right ]$

To expand on CaptainBlack's "no," please be aware that it is better for everyone on the site to have the solution posted here so someone else who wants to learn the process can do so and ask questions about it. If the solution is simply sent to your e-mail others will not benefit as well.

-Dan

I was trying to avoid being too helpfull :(

RonL
• Jun 15th 2006, 11:07 AM
topsquark
Quote:

Originally Posted by CaptainBlack
I was trying to avoid being too helpfull :(

RonL

Oops! :o

-Dan
• Jul 18th 2006, 01:24 AM
CaptainBlack

RonL
• Jul 18th 2006, 02:56 AM
Soroban
Hello, Lalit!

Who assigned this hideous problem . . . Torquemada?
. . (No one expects the Spanish Inquisition!)

Quote:

Given: . $A = \begin{pmatrix}2&12&18\\13&15&20\\19&17&1\end{pmat rix}\;\;B = \begin{pmatrix}12&2&1\\13&14&21\\9&18&7\end{pmatri x}\;\;C = \begin{pmatrix}12&2&7\\30&18&22\\9 &16&4\end{pmatrix}$

Find: . $A^{-1} \times B \times (-C)$

Thanks to topsquark's work, all you have to do is:

. . $\frac{1}{2602}\begin{pmatrix}\text{-}134355&\text{-}142196&\text{-}84492\\43995&92792&21298\\\text{-}45192&\text{-}57048&\text{-}23892\end{pmatrix}\,\begin{pmatrix}12&2&1\\13&4&2 1\\9&18&7\end{pmatrix}$ $\begin{pmatrix}\text{-}12&\text{-}2&\text{-}7\\\text{-}30&\text{-}18&\text{-}22\\\text{-}9&\text{-}16&\text{-}4\end{pmatrix}$

Good luck!