Answer:
-1
Step-by-step explanation:
Vector a=(1,0) if visualized as a line has points (0,0) and (1,0). This means the line is horizontal and has equation y=0.
This means we are looking for a vertical line.
Instead of lambda, I'm going to use u.
So we want a+ub=(1,0)+u(1,1). to vertical. If we visualize this as a line with points (0,0) and (1+u,u). We would need u=-1 so this would be vertical.
So vectors a=(1,0) and a+ub=(1,0)+u(1,1) are perpendicular for u=-1.
So we are saying vectors (1,0) and (0,-1) are perpendicular. If you draw these, you can get a visual confirmation.
