Question

a motorboat moves across a lake as a constant speed. when it begins, it is 50 km from the shore. after 9 minutes, it is 14 km from the shore. which function describes the motorboat's distance from the shore? A. y=-9x+50 B. y=4x+50 C. y=-4x+50 D. y=9x+50

Answer 1

Answer:

The function describes the motorboat's distance from the shore $y=-4x+50$

Step-by-step explanation:

A motorboat moves across a lake as a constant speed. when it begins, it is 50 km from the shore

After 9 minutes, it is 14 km from the shore.

So, rate of change = $\frac{\text{Final distance}-\text{Initial distance}}{time}=\frac{14-50}{9}=-4$

Negative sign shows that there is decrease in distance per minute

The rate of change of distance is 4 km / minutes

General equation : y = mx+c

Where m is the slope and c is the constant

Substitute the values in the equation :

y=-4x+50

Where y is the final distance and x is the minutes

So, Option C is true

Hence The function describes the motorboat's distance from the shore $y=-4x+50$