## Urgent homework help!! Orthonormal vectors?

1) Find the orthonormal vectors q1, q2, q3 such that q1, q2 span the column space of:

A = [1 1
2 -2
-2 4]

2) Which of the 4 fundamental subspaces contains q3?

3) Solve Ax = (1,2,7) by least squares

No idea how to solve this... please show steps?