Question

The water level of a river is 170 feet. The river recedes 4 feet each year. Ingrid claims that the equation that represents this scenario is y = 170x – 4. Is her equation correct? Explain.

Answer 1

No, Ingrid is incorrect. The initial value in the scenario is 170 feet, which represents the y − intercept. Receding 4 feet in the scenario represents the rate of change, which is the slope. In slope-intercept form, y = mx + b, where m represents slope and b represents the y−intercept, so the correct equation is y = −4x + 170.

Explanation: