Answer (1) y =; (2) The practical significance of m (3, 120): When they leave for 3 hours, it is120km; Away from their respective starting points; (3) Hours and 4 hours later, the two cars meet.

Analysis?

Test analysis: (1) According to A to B, we know that the polyline image is the function image of A immediately, and then divide it into 0≤x≤2 and 2.