reducing matrix ??

raneem · 2012-05-07 22:02:59

HI everyone,
could you help me with this problem!!??
Reduce this matrix....i tried to solve it but I did not know how??

x+x-2x+x=9
x-x+2x=1
x-3x=5

1 1 -2 1 9
0 1 -1 2 1
0 0 1 -3 5

my level is university

thank you...

Bob · 2012-05-07 22:12:39

hi raneem

Welcome to the forum!

That question seems odd to me. Too many xs.

I'd expect w, x, y, z in a question like this.

Then reducing it would mean doing row and column operations that lead to z = .... y = ...... x = ...... w = ......

But with 4 unknowns and only three equations you won't get a unique solution.

You could express each of w, x and y in terms of z.

You could try:

The screen shot below shows what I got from this.

Bob

raneem · 2012-05-07 23:14:38

Thank You Very Much !

Bob · 2012-05-07 23:16:17

You're welcome! Are you ok with this now?

Bob

raneem · 2012-05-08 00:44:28

please can you check if it is right

1st row
x-4x=9
-3x=9
x=-3
ـــــــــــــــــــــــــــــــ
2nd row
0=6
ـــــــــــــــــــــــــــــــ
3rd row
x-3x=5
-2x=5
x=-5\2

i think there is no answer because 2nd row equal zero ..... right

Bob · 2012-05-08 00:59:38

hi raneem

your matrix layout is very hard to follow.

Time for a lesson in using Latex.

Start a line with square brackets math

and end with square brackets /math

Between the math instructions put the following

\left|
\begin{array}{c c c c c}
1 & 1 & -2 & 1 & 9 \\
& 1 & -1 & 2 & 1 \\
& & -1 & -3 & 5
\end{array}
\right|

This will result in the following:

Then you can show what you are doing properly.

Bob

Math Is Fun Forum