Question

A businesswoman buys a new computer for $4000. For each year that she uses it the value depreciates by $400. The equation y=-400x+4000 gives the value y of the computer after x years. What does the x-intercept mean in this situation ? Find the x-intercept. After how many years will the value of the computer be $2000 ?

Answer 1

We have the following:

The intersection with the x-axis is when the value of y is 0, that is, the computer already has a value of 0 and has no commercial value.

we found it like this

`\begin{gathered} 0=-400x+4000 \\ 400x=4000 \\ x=(4000)/(400) \\ x=10 \end{gathered}`

which means that in 10 years, the computer does not represent a commercial value

to calculate the number of years that have passed when the computer has a value of 2000, y = 2000, therefore we replace

`\begin{gathered} 2000=-400x+4000 \\ 400x=4000-2000 \\ x=(2000)/(400) \\ x=5 \end{gathered}`

This means that in a total of 5 years the value of the computer will be $ 2000