Matrix....

This is a school assignment...so I am not looking for anyone to do it for me...but I need some help on the way to get started with this one...

Here we go....

I have a matrix A:

1, 1, 1-t
1, 0, t
t+1, 1, 1

and a matrix B:
4, 1, 1
3, 1, 1
5, 1, 1

and a matrix X that is 3*3. When t = 2 we have that

AX = B + X

What is the X matrix....???

We have just started with matrixes so I ain't any good, so I am not sure what I am allowed to do with them. Can I move any of them to the other side? Or where can I start??? Any help are appreciated...

I don't know of any stuff you could do with this AX=b+ X.
to determine X I think you must use all equations seperatly.
So you know AX (1,1) is the Sum of a(1,1)*x(1,1)+ a(1,2)*x(2,1)+a(1,3)*x(3,1). Do that for all items of AX. Since the Summ of the matrici b+X is b(1,1)+(x(1,1) and so forth.
To detemine the values for X use the individual equations from AX=B+X

For a start:
First column of AX would be:
AX(1,1)= x(1,1)+x(2,1)-x(3,1)
AX(2,1)=x(1,1)+2x(3,1)
AX(3,1)=3x(1,1)+x(2,1)+x(3,1)

B(1,1)+x(1,1)=4+x(1,1)
B(2,1)+x(2,1)=3+x(2,1)
b(3,1)+x(3,1)=5+x(3,1)

You should be able to solve for x(1,1); x(2,1) ; x(3,1)


I could do it, and it was the first time working with matrici since I had that at university about 20 years ago!

I just got an idea....before I saw your post Opus....

Here we go...

We have:
AX = B + X

We multiplay with X^-1

then we have:

A = BX^-1 + I

Then we have:

A - I = BX^-1

We move B over and do it inverse:

B^-1 (A -I ) = X^1

Then we do everything inverse:

B (A - I)^-1 = X:


It was so simple all the time...The equation over here is so simple to solve....I am so happy now...

BTW Thanks Opus. I was first thinking the way you where thinking. But it didn't look "right"...it had to be a simpler way to do it...and I found it. But thanks anyway. You are a great man. Nice to see that you havn't forgott math in 20 years..;)

/me totaly ashamed:cool:

Greetings to the North! Is it already day in Norway?

I have been up in 6,5 hours alreaddy...;)....I am soon halfway thrue my day....and you don't have to be ashamed. You tried to help me. And are the only one who did. So you should have the greetings...;)