Question

Which graph could represent a car that begins by increasing its speed, then travels at a constant speed, and then decreases its speed, as time increases? A graph with time (minutes) on the horizontal axis and speed (miles per minute) on the vertical axis. Both axes are unnumbered. The speed begins at 0, goes up at first, is steady for a while, and then goes down over time. A graph with time (minutes) on the horizontal axis and speed (miles per minute) on the vertical axis. Both axes are unnumbered. The speed begins in the middle of the vertical axis, goes down at first, is steady for a while, and then goes up over time. A graph with time (minutes) on the horizontal axis and speed (miles per minute) on the vertical axis. Both axes are unnumbered. The speed begins at 0, goes up at first, goes down for a while, and then is steady over time. A graph with time (minutes) on the horizontal axis and speed (miles per minute) on the vertical axis. Both axes are unnumbered. The speed begins in the middle of the vertical axis, goes down at first, goes up for a while, and then is steady over time. Mark this and return

Answer 1

• It is the first graph, whose description is: The speed begins at 0, goes up at first, is steady for a while, and then goes down over time.

Step-by-step explanation:

Since the speed is on the vertical axis:

• the first stage shows that the car begins with speed 0 and increases its speed,

• then, the second stage shows that it travels a constant speed (constant speed is a steady line, i.e. paralell to the horizontal axis), and

• the third stage shows the reduction (decrease) of the speed.

In general, lines with positive slope are increasing functions, lines with negative slope are decreasing functions, and horizontal lines (slope = 0) are constant functions.