Let and .

Compute .

Compute .

Solve the normal equations to determine the set of least-squares solutions.

Compute .

Compute .

Solve the normal equations to determine the set of least-squares solutions.

Why is there only one least-squares solution?

Let and .

Compute .

Compute .

Solve the normal equations to determine the set of least-squares solutions.

Compute .

Compute .

Solve the normal equations to determine the set of least-squares solutions.

When will the method of solving the normal equations, , work for finding the
least-squares solutions?