Originally Posted by

**Skelly** I was just trying to solve a couple of questions from the past exam tests and I've got the following answer for this question. Can someone check if my answer is right. I am not so sure. Thanks!

Let,

A = [ 1 1 0

1 1 0

1 0 1

1 0 1]

and b = [1,3,8,2]^T. Find the least squares solutions of the system Ax=b.

ANSWER:

The general least squares solution to this sort of problem is:

x = ((A^T)A)^(-1)*((A^T)*b)

In this case this will not yield a solution, since you have two pairs of identical rows, the A matrix represents only 2 independent realtions. As such, ((A^T)A) is singular so no solution exists.