CHAPTER 3 SECTION 3.7 OPTIMIZATION PROBLEMS
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CHAPTER 3 SECTION 3.7 OPTIMIZATION PROBLEMS. Applying Our Concepts. We know about max and min … Now how can we use those principles?. 60”. x. 30”. Use the Strategy. What is the quantity to be optimized? The volume What are the measurements (in terms of x)?
CHAPTER 3 SECTION 3.7 OPTIMIZATION PROBLEMS
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Applying Our Concepts • We know aboutmax and min … • Now how can we use thoseprinciples?
60” x 30” Use the Strategy • What is the quantity to be optimized? • The volume • What are the measurements (in terms of x)? • What is the variable which will manipulated to determine the optimum volume? • Now use calculus principles
Optimization Maximizing or minimizing a quantity based on a given situation Requires two equations: Primary Equation what is being maximized or minimized Secondary Equation gives a relationship between variables
1 Write it in terms of one variable. 2 Find the first derivative and set it equal to zero. 3 Check the end points if necessary. To find the maximum (or minimum) value of a function:
1. An open box having a square base and a surface area of 108 square inches is to have a maximum volume. Find its dimensions.
1. An open box having a square base and a surface area of 108 square inches is to have a maximum volume. Find its dimensions. Primary Secondary Domain of x will range from x being as small as possible to x as large as possible. Largest (y is near zero) Smallest (x is near zero) Intervals: Test values: V ’(test pt) V(x) rel max Dimensions: 6 in x 6 in x 3 in
2. Find the point on that is closest to (0,3). Minimize distance Secondary Primary ***The value of the root will be smallest when what is inside the root is smallest. Intervals: Test values: d ’(test pt) d(x) rel min rel max rel min
2. A rectangular page is to contain 24 square inches of print. The margins at the top and bottom are 1.5 inches. The margins on each side are 1 inch. What should the dimensions of the print be to use the least paper?
2. A rectangular page is to contain 24 square inches of print. The margins at the top and bottom are 1.5 inches. The margins on each side are 1 inch. What should the dimensions of the print be to use the least paper? Primary Secondary Largest (y is near zero) Smallest (x is near zero) Intervals: Test values: Print dimensions: 6 in x 4 in A ’(test pt) A(x) Page dimensions: 9 in x 6 in rel min
1. Find two positive numbers whose sum is 36 and whose product is a maximum.
1. Find two positive numbers whose sum is 36 and whose product is a maximum. Primary Secondary Intervals: Test values: P ’(test pt) P(x) rel max
There must be a local maximum here, since the endpoints are minimums. A Classic Problem You have 40 feet of fence to enclose a rectangular garden along the side of a barn. What is the maximum area that you can enclose?
A Classic Problem You have 40 feet of fence to enclose a rectangular garden along the side of a barn. What is the maximum area that you can enclose?
Example 5: What dimensions for a one liter cylindrical can will use the least amount of material? Motor Oil We can minimize the material by minimizing the area. We need another equation that relates r and h: area of ends lateral area
Example 5: What dimensions for a one liter cylindrical can will use the least amount of material? area of ends lateral area
Notes: If the function that you want to optimize has more than one variable, use substitution to rewrite the function. If you are not sure that the extreme you’ve found is a maximum or a minimum, you have to check. If the end points could be the maximum or minimum, you have to check. p
r h Example #1 • A company needs to construct a cylindrical container that will hold 100cm3. The cost for the top and bottom of the can is 3 times the cost for the sides. What dimensions are necessary to minimize the cost.
Minimizing Cost Domain: r>0
1.744 0 Minimizing Cost Concave up – Relative min - - - - - - + + + + + C' changes from neg. to pos. Rel. min The container will have a radius of 1.744 cm and a height of 10.464 cm