Let me point out that the equation you give is of a line through (4, 0, 5) (just take t= 0). What does the (-3,1,2) represent?
Well, you know that in the xy-plane, z= 0. What is the value of the parameter when z= 0? In the xz-plane, y= 0. What is the value of the parameter when y= 0?b) Find also the coordinates of the points where L meets the xy-plane and the xz-plane.
Thank you in advance