Chapter 5: Problem 89
When is it easier to use the addition method rather than the substitution method to solve a system of equations?
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Chapter 5: Problem 89
When is it easier to use the addition method rather than the substitution method to solve a system of equations?
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Solve the systems $$\left\\{\begin{array}{l} \log _{y} x-3 \\ \log _{y}(4 x)-5 \end{array}\right.$$
Group members should choose a particular field of interest. Research how linear programming is used to solve problems in that field. If possible, investigate the solution of a specific practical problem. Present a report on your findings, including the contributions of George Dantzig. Narendra Karmarkar, and L. G. Khachion to linear programming.
Sketch the graph of the solution set for the following system of inequalities: $$\left\\{\begin{array}{l} y \geq n x+b(n<0, b>0) \\ y \leq m x+b(m>0, b>0). \end{array}\right.$$
On June \(24,1948,\) the former Soviet Union blocked all land and water routes through East Germany to Berlin. A gigantic airlift was organized using American and British planes to bring food, clothing, and other supplies to the more than 2 million people in West Berlin. The cargo capacity was \(30,000\) cubic feet for an American plane and \(20,000\) cubic feet for a British plane. To break the Soviet blockade, the Western Allies had to maximize cargo capacity but were subject to the following restrictions: \(\cdot\) No more than 44 planes could be used. "The larger American planes required 16 personnel per flight, double that of the requirement for the British planes. The total number of personnel available could not exceed 512 \(\cdot\) The cost of an American flight was \(\$ 9000\) and the cost of a British flight was \(\$ 5000 .\) Total weekly costs could not exceed \(\$ 300,000\) Find the number of American and British planes that were used to maximize cargo capacity.
a. A student earns \(\$ 10\) per hour for tutoring and \(\$ 7\) per hour as a teacher's aide. Let \(x=\) the number of hours each week spent tutoring and let \(y=\) the number of hours each week spent as a teacher's aide. Write the objective function that models total weekly earnings. b. The student is bound by the following constraints: \(\cdot\) To have enough time for studies, the student can work no more than 20 hours per week. \(\cdot\) The tutoring center requires that each tutor spend at least three hours per week tutoring. \(\cdot\) The tutoring center requires that each tutor spend no more than eight hours per week tutoring. Write a system of three inequalities that models these constraints. c. Graph the system of inequalities in part (b). Use only the first quadrant and its boundary, because \(x\) and \(y\) are nonnegative. d. Evaluate the objective function for total weekly earnings at each of the four vertices of the graphed region. [The vertices should occur at \((3,0),(8,0),(3,17), \text { and }(8,12) .]\) Complete the missing portions of this statement: The student can earn the maximum amount per week by tutoring for hours _____ per week and working as a teacher’s aide for _____ hours per week. The maximum amount that the student can earn each week is $_____.
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