Question

The floor of a canyon has an elevation of −14.5feet. Erosion causes the elevation to change by −1.5 feet per year. How many years will it take for the canyon floor to have an elevation of −31

Answer 1

11 years

work:

-31-14.5=-16.5

16.5/1.5= 11

11 is the answer

Answer 2

For this case, the first thing we must do is define variables.

We have then:

x: number of years

y: elevation in feet

Then, we write the equation that models the problem.

We have then:

`image`

Then. for an elevation of -31 feet we have:

`image`

From here, we clear the number of years.

We have then:

`image`

`image`

Answer:

It will take for the floor to have an elevation of -31 about 11 years.