In your notes, write down a strategy for solving for x- and y-intercepts. Use the following example to solve for the x-intercept, y-intercept, and the zero of the function. Describe what those points mean in this problem situation.

Problem:  A diver explored the ocean floor 120 feet below the surface and then ascended at a rate of 30 feet per minute. The equation, 30t − e = 120, describes the diver’s elevation, e, below sea level during his ascent in t minutes.  Find the x-intercept, y-intercept, and the zero of the function.

Check Your Answer

First, you should consider your ordered pair of time and elevation, (t, e).

Your x-intercept is your time at an elevation of 0.

30t – e 30t – 0 30t___ 30

= 120 = 120 = 120 30

So, the x-intercept is 4 minutes representing the time that the diver reaches the surface, or depth = 0.  (4, 0)

Your y-intercept is your elevation at the start of the ascent, time = 0 min.

30t – 0 30(0) – e – e e

= 120 = 120 = 120 =-120

So, the y-intercept is -120 feet in elevation representing the depth of 120 feet at the beginning of the ascent, t = 0.  (0, -120)

The zero of the function is the x-value of the x-intercept, so the zero is 4.