Answer:
5 trees should be planted to maximize the yield per acre,
The maximum yield would be 1250
Step-by-step explanation:
Given,
The original number of trees per acre = 20,
Average pounds of nuts by a tree = 60,
Let x be the times of increment in number of trees,
So, the new number of trees planted per acre = 20 + x
∵ for each additional tree planted per acre, the average yield per tree drops 2 pounds,
So, the new number of pounds of nut = (60 - 2x)
Thus, the total yield per acre,
![Y(x) = (20+x)(60-2x)](https://tex.z-dn.net/?f=Y%28x%29%20%3D%20%2820%2Bx%29%2860-2x%29)
Differentiating with respect to t ( time ),
![Y'(x) = (20+x)(-2) + 60 - 2x = -40 - 2x + 60 - 2x = 20 - 4x](https://tex.z-dn.net/?f=Y%27%28x%29%20%3D%20%2820%2Bx%29%28-2%29%20%2B%2060%20-%202x%20%3D%20-40%20-%202x%20%2B%2060%20-%202x%20%3D%2020%20-%204x%20)
Again differentiating with respect to t,
![Y''(x) = -4](https://tex.z-dn.net/?f=Y%27%27%28x%29%20%3D%20-4)
For maxima or minima,
![Y'(x) = 0](https://tex.z-dn.net/?f=Y%27%28x%29%20%3D%200)
⇒ 20 - 4x = 0
⇒ 20 = 4x
⇒ x = 5,
For x = 5, Y''(x) = negative,
Hence, Y(x) is maximum for x = 5,
And, maximum value of Y(x) = (20+5)(60 - 10) = 25(50) = 1250,
i.e. 5 trees should be planted to maximize the yield per acre,
and the maximum yield would be 1250 pounds