Inverting a 3x3 matrix - can't figure out where I've gone wrong

Hi, currently really stuck on this question because I followed the normal procedure for inverting a 3x3 matrix but I'm getting a different answer from the given solution. I will post a picture of my work below so would greatly appreciate if you can help me work this out xx

Original post by olivier_

Your 17/8 should be -17/8.

Not checked further.

Reply 3

tonyiptony

Hmm... beyond what ghostwalker has said, it doesn't seem like you have actually finished the Gauss-Jordan/ERO yet (whatever you call this method of matrix inversion)?

Your goal is to manipulate the left hand side of the augmented matrix to be precisely the identity matrix.

(edited 1 year ago)

Reply 4

olivier_