To find the value of the computer equipment 5 years after it was purchased, we can substitute $x = 5$ into the given equation:

$y = 4000(0.87)^x$

Substitute $x = 5$:

$y = 4000(0.87)^5$

Now, we calculate:

$y = 4000 \times (0.87)^5$

$y = 4000 \times 0.513$

$y \approx 2052$

So, the value of the computer equipment 5 years after it was purchased is approximately $2,052.

Would you like further details or have any questions? Here are some related questions for you:

1. What is the rate of depreciation in this model?
2. How much is the equipment worth after 10 years?
3. How do exponential decay models compare to linear decay models?
4. What does the base $0.87$ represent in this context?
5. How would the value change if the rate of depreciation were increased to $0.90$?

Tip: In exponential decay, the base of the exponent is always less than 1, showing how the value decreases over time.