Question

plzzz help A model train is on a track 100 cm from its starting point. Turning a switch displaces the train either forward or backward 25 cm along the track depending on which way the switch is turned. Which equation models the position of the train along the track after you turn the switch? A. |x − 25| = 100 B. |x − 100| = 25 C. |x + 25| = 100 D. |x + 100| = 25

Answer 1

Answer: B.  |x-100| = 25

Explanation:

Draw out a number line. Mark 75, 100 and 125 on the number line as points A, B, and C in that order. Don't worry about the spacing.

The value of x represents where the train is. So if we had say x = 85, then it would be at location 85 on the number line. Writing |x-100| is the distance from x to 100. The absolute value ensures the distance is never negative. We want this distance to be 25 because after traveling 25 cm, the switch is turned, and the train goes the other way.