Linear Least Square in Matlab

Question

I read about multilateration method and solving it using Least Square method. Assuming I have (m) points in 2-D, and their distances(the distances contain error), then I want to find the intersection point.

In (linear form) least square method the equations are:

Ax =b

In Matlab when use:

x= A\b

or

x= lsqr(A,b)

It gives only one answer! does it give the best solution directly?

And how I can get all the solutions?

Thanks,