A hot air balloon's path is modeled using the function f(x)=−x2+150

𝑓
(
𝑥
)
=

𝑥
2
+
150
. A mine shaft elevator's path is modeled using the equation g(x)=−20x
𝑔
(
𝑥
)
=

20
𝑥
. In both instances, the domain is time, in minutes, and the range is height, in meters. Using GeoGebra, graph the two situations. Which statement correctly interprets the graphs? (1 point)
Responses

Negative range values don't make sense for either scenario.
Negative range values don't make sense for either scenario.

Positive domain values don't make sense for either scenario.
Positive domain values don't make sense for either scenario.

The starting point of the balloon is higher than that of the elevator.
The starting point of the balloon is higher than that of the elevator.

The balloon will reach the ground before the elevator car does.

1 answer

To interpret the functions and their graphs:

  1. Hot Air Balloon: \( f(x) = -x^2 + 150 \)

    • This function represents a downward-opening parabola with a maximum height of 150 meters (when \( x = 0 \)). The vertex of this parabola, which is the maximum height, occurs at \( x = 0 \), and as time increases, the height decreases.
  2. Mine Shaft Elevator: \( g(x) = -20x \)

    • This function represents a straight line with a constant negative slope of -20, meaning that for each minute, the elevator drops 20 meters starting from a height of 0 meters (when \( x = 0 \)). Thus, it can be interpreted that it descends continuously.

Now, examining the options:

  • Negative range values don't make sense for either scenario: This option is true because height (range) cannot be negative in either scenario (the balloon can't go below ground level and the elevator cannot go below its starting point).

  • Positive domain values don't make sense for either scenario: This is incorrect. Positive values for time (domain) do make sense as both the balloon and the elevator can be observed over minutes.

  • The starting point of the balloon is higher than that of the elevator: This is also true since the balloon starts at a height of 150m, while the elevator starts at 0m.

  • The balloon will reach the ground before the elevator car does: This is not necessarily true. The parabola and the linear function must be analyzed further for intersection, but generally, the balloon will reach the ground after descending for a while.

Based on this analysis, the best choice would be:

Negative range values don't make sense for either scenario.

This option directly addresses the validity of negative heights in both scenarios. Additionally, a secondary correct observation could be that the starting point of the balloon is higher than that of the elevator. But the most universally significant statement is about negative range values.