Why do I keep getting an infinity loop when I try to implement the Jacobi method?

I derived B from this linear system:

1a - 1b + 2c= 8 
1a + 1b + 2c = 10
1a + 0b + 1c = 2

clear all;clc;
c=[8 10 2]';
B= [0 1 -2;-1 0 -2;-1 0 0];
tol = 10^(-10);
x0=[1,1,1]'; x(:,1)= x0;
k=1;
while 1
    xnew(:,k+1) = (B*x(:,k)) + c;
    if norm(xnew(:,k+1)-x(:,1)) < tol
        break;
    end
x=xnew;
k=k+1;
end
k

[Walter Roberson]

How the heck does your B array relate to the system of equations you indicate? And why are you adding c instead of subtracting it?