.
Write the function A(n) as a quadratic function in the standard form
A(n) = (600+n)*(10-0.01n) = 6000 + 10n - 6n - 0.01n^2 = - 0.01n^2 + 4n + 6000.
Any quadratic function y(x) = ax^2 + bx + c with the negative leading coefficient "a" has the maximum at x = .
In this case, the quadratic function A(n) has coefficients a = -0.01, b = 4.
Therefore, it gets the maximum value at n = = = 200.
ANSWER. 200 ADDITIONAL vines per acre will provide the maximum of grape production.
In all, 600+200 = 800 vines should be planted.
Solved.
-------------------
On finding the maximum/minimum of a quadratic function see the lessons
- HOW TO complete the square to find the minimum/maximum of a quadratic function
- Briefly on finding the minimum/maximum of a quadratic function
- HOW TO complete the square to find the vertex of a parabola
- Briefly on finding the vertex of a parabola
- A rectangle with a given perimeter which has the maximal area is a square
- A farmer planning to fence a rectangular garden to enclose the maximal area
- A farmer planning to fence a rectangular area along the river to enclose the maximal area
- A rancher planning to fence two adjacent rectangular corrals to enclose the maximal area
- Using quadratic functions to solve problems on maximizing revenue/profit (*)
Do not miss the lesson marked (*) in the list, since it contains many similar solved problems, closed to yours in your post.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the topic "Finding minimum/maximum of quadratic functions".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.