Can you find the least-squares solution and projection of this matrix equation?

[mivanova]

I really need your help with this.
Let A = (1 -2
-1 2
0 3
2 5)
and b = ( 3
1
-4
2)

(a) Find a least-squares solution of Ax = b.
(b) Find the orthogonal projection of b onto the column space of A.
(c) Compute the least-squares error ( in the solution of part ( a )).
Thank you!

 

[HallsofIvy]

What do you want? It is impossible to give hints if we don't know what you have done and where you are stuck. And we can only tell that by seeing what you have tried.