College

Write an equation to model the situation where Captain Brain and Mr. Pinky start at a depth of 1500 feet underwater and ascend to 1380 feet below the surface after 6 hours. Use [tex]d[/tex] for depth in meters and [tex]x[/tex] for hours.

Answer :

Variables

d: depth, in ft

x: time, in hours

The first point is (0, -1500) that is, at zero hours, they were 1500 ft underwater

The second point is (6, -1380), that is, at six hours, they were 1380 ft underwater

The slope of the line that connects these two points is:

[tex]m=\frac{-1380-(-1500)}{6-0}=\frac{120}{6}=20\frac{ft}{h}[/tex]

From the point (0, -1500) the y-intercept of the line is b = -1500

Using the slope-intercept form of the line we get:

y = mx + b

d = 20x - 1500