A train starts from a, passes station B and goes to station C. the distance between station a and station B is 100 km. After leaving the station, the train advances at the speed of 3 / 4 per minute for t minutes How many kilometers is the train from station B and station a

A train starts from a, passes station B and goes to station C. the distance between station a and station B is 100 km. After leaving the station, the train advances at the speed of 3 / 4 per minute for t minutes How many kilometers is the train from station B and station a

100 ÷ (3 / 4) = 400 / 3 (seconds)
1) When t ≤ 400 / 3
From station B: 100-3 / 4T km
3 / 4T km away from station a
2) When t > 400 / 3
From station B: 3 / 4t-100km
3 / 4T km away from station a

The train leaves the station at an average speed of 75KM / h at a place 5km away from the station. The functional relationship between the distance x (km) between the train and the station and the train travel time t (H) is obtained, and whether s is a linear function of T or a positive proportional function is judged

X = 5 + 75t, is a linear function, not a positive scale function, because the style of positive scale function is: y = KX

If the train leaves the station at a constant speed of 75 km / h from a place 5 km away from the station, the functional relationship between the distance s (km) between the train and the station and the train travel time t (H) is_______ The value range of the independent variable t is________

s=5+75t t>=0