### Corresponding value of a parameter

Hello,
I am quite new to Sage and I have the following question.
In my computations I have a quadratic form: **$x^T A x = b $** ,
where the matrix A is defined already as a symmetric matrix, and x is defined as

~~W ~~import itertools
X = itertools.product([0,1], repeat = n)
for ~~w ~~x in ~~W: w ~~X:
x = ~~vector(w)
~~vector(x)
print x

as all combination of $[0,1]$ repeated n times. I got a set of values for **$b$** and extracted few of them from the set. Now, I need to identify which **$x$** is corresponding to a particular value of **$b$**. Is there any command to do so? If it is possible. Thank you for help.