Return line segment function: let y = aX+b substitute points (60,6) and (80, 1).
Get the function: y = -0.25x+2 1.
So yes, the estimated time to return to the county seat is t = 84.
As can be seen from the meaning of the question, it is one minute later than expected, so the intersection point on the graph is (85,0).
Answer:
(1) As can be seen directly from the figure, the meeting is at t =20, so the initial segment function is brought in to get y = 4.
That is, meet at a place 4 kilometers away from the county seat.
② According to the analysis steps, it took 85 minutes.
(3) Let Li Ming walk the distance of X from t = 0 to t = 20.
According to similar triangles, x = 1.
So, when the postman Xiao Wang set off, Li Ming was 5 kilometers away from the county seat.
Set to 0 =
Substitution points (0,5) and (80, 1)
Get y = -0.05x+5, take y = 6, then x = -20.
So Li Mingyi walked for 20+85 = 105 minutes.
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