Matrix question?

Question

Find N so that NM = I . How do i create an equation to find the matrix N?

the matrix of M is
1 2 0
2 1 0
0 2 1

From a previous question, i've found the matrix of N which is
0 4 0
0 0 4
4 0 0

Answer 1

here is described howto invert a matrix. ( you are trying to invert the matrix M )

http://www.purplemath.com/modules/mtrxinvr.htm

start reading halfway the page wher it says "Find the inverse of the following matrix."
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