How to make a constraint for restricting two vectors on one line?

b=[1 1 1];c=[2 6];
A=[1 3 5;8 6 9];B=[6 2 8; 8 4 5];
variables x(3) ;variables y(3);
minimize( b*abs(x)+b*abs(y));
subject to

i want to restrict vector x and vector y on one line, i mean that


and i make a constraint as follows:


but this is Invalid constraint: {convex} <= {convex}
how can i express this constraint in CVX ?
this constraint is very important in my modle, thanks very much.

I do not think it is possible to express it as a convex problem. Please explain why you think it should be convex!