See, please, suggested decision: When the line intersects the xy-plane, then parameter z=0, when does the xz - y=0 and when does yz, x=0. All the details are in attachment. If it's possible, check arithmetic part.
Well x=1 always unless it tells you other wise so 1+0.5 would equal 1.5 and so after that you keep adding so 1.5 + 0.5 equal 2 so you keep taking the previous answer and adding 0.5 to it