Question

After 3 minutes, a submarine had descended to −320 feet. After 8 minutes, the submarine had descended to −420 feet. Assuming a linear function, write an equation in the form d(t)=mt+b that shows the depth, d(t), after t minutes.

Answer 1

Answer:

  d(t) = -20t -260

Step-by-step explanation:

We are given two points ...

  (t, d) = (3, -320) and (8, -420)

The 2-point form of the equation of a line can be useful when 2 points are given.

  y = (y2 -y1)/(x2 -x1)(x -x1) +y1

Substituting the given points, we have ...

  d(t) = (-420 -(-320))/(8 -3)(t -3) -320

  d(t) = -20(t -3) -320

  d(t) = -20t -260