# Thread: Working with identity and transpose matrices

1. ## Working with identity and transpose matrices

hi everyone,

im trying to solve (I - A(transpose))y = c

i tried to do this in 2 different methods. can you please see my files attached?
method 1...i have followed all the rules of mathematics properly (no??) and i got a different (wrong) answer, compared to method 2. why is this? does anyone know? what rule am i breaking or what am i not doing?

thank you all!!

2. Well, your Method 1 is solving the equation $\displaystyle (I-A)y=c,$ not $\displaystyle (I-A^{T})y=c.$ That could be part of the problem. You've skipped too many steps for me to easily see what might be going on in Method 2.

3. method 1
line before last line 4(2x-10)=8x-40 not 8x-10

4. actually i copied and pasted wrong in word. i will redo it.
i copied in matrix A , when my working was correct. i.e. (I - At ) y = c working is correct. i will try to make this clearer

5. ah thanks!! wow. completely missed that :/