Question

Write an absolute value inequality to represent each situation.

Two friends are hiking in Death Valley National Park. Their elevation ranges

from 228 ft below sea level at Badwater to 690 ft above sea level at Zabriskie

Point. Let x represent their elevation in feet.

Answer 1

║ x - 231 ║ ≤ 459

Explanation:

Since we have 228 ft below sea level, this is x' = -228 ft. Also, we have 690 ft above sea level, this is x" = 690 ft.

Since x is our elevation in feet, x ranges from -228 ≤ x ≤ 690.

To write an absolute value equation for x, we first take the average of the two values for the ranges to obtain the ideal value of x.

So, ideal value = [690 + (-228)]/2 = 462/2 = 231.

We also find the tolerance by taking the difference of both values and dividing by 2. So tolerance = [690 - (-228)]/2 = [690 + 228)]/2 = 918/2 = 459.

Subtracting 231 from each value of the inequality we have

-228 - 231 ≤ x - 231 ≤ 690 - 231

-459 ≤ x - 231 ≤ 459

Since we have in magnitude the values on the left and right side of the inequality,

So ║ x - 231 ║ ≤ 459