Calculus, Early Transcendentals
9th Edition
ISBN: 9781337613927
Author: Stewart
Publisher: CENGAGE L
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Textbook Question
Chapter 9.3, Problem 46E
A certain small country has $10 billion in paper currency in circulation, and each day $50 million comes into the country’s banks. The government decides to introduce new currency by having the banks replace old bills with new ones whenever old currency comes into the banks. Let x = x(t) denote the amount of new currency in circulation at time t, with x(0) = 0.
(a) Formulate a mathematical model in the form of an initial-value problem that represents the “flow” of the new currency into circulation.
(b) Solve the initial-value problem found in part (a).
(c) How long will it take for the new hills to account for 90% of the currency in circulation?
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Chapter 9 Solutions
Calculus, Early Transcendentals
Ch. 9.1 - Write a differential equation that models the...Ch. 9.1 - Write a differential equation that models the...Ch. 9.1 - Prob. 3ECh. 9.1 - Prob. 4ECh. 9.1 - Prob. 5ECh. 9.1 - Determine whether the given function is a solution...Ch. 9.1 - Determine whether the given function is a solution...Ch. 9.1 - Prob. 9ECh. 9.1 - Prob. 12ECh. 9.1 - Show that the given function is a solution of the...
Ch. 9.1 - Prob. 14ECh. 9.1 - (a) For what values of r does the function y = erx...Ch. 9.1 - (a) For what values of k does the function y = cos...Ch. 9.1 - Which of the following functions are solutions of...Ch. 9.1 - (a) Show that every member of the family of...Ch. 9.1 - (a) What can you say about a solution of the...Ch. 9.1 - (a) What can you say about the graph of a solution...Ch. 9.1 - A population is modeled by the differential...Ch. 9.1 - The Fitzhugh-Nagumo model for the electrical...Ch. 9.1 - Explain why the functions with the given graphs...Ch. 9.1 - The function with the given graph is a solution of...Ch. 9.1 - Match the differential equations with the solution...Ch. 9.1 - Suppose you have just poured a cup of freshly...Ch. 9.1 - Psychologists interested in learning theory study...Ch. 9.1 - Von Bertalanffys equation states that the rate of...Ch. 9.1 - Differential equations have been used extensively...Ch. 9.2 - A direction field for the differential equation y'...Ch. 9.2 - A direction field for the differential equation...Ch. 9.2 - Match the differential equation with its direction...Ch. 9.2 - Match the differential equation with its direction...Ch. 9.2 - Match the differential equation with its direction...Ch. 9.2 - Match the differential equation with its direction...Ch. 9.2 - Prob. 7ECh. 9.2 - Use the direction field labeled III (above) to...Ch. 9.2 - Sketch a direction field for the differential...Ch. 9.2 - Sketch a direction field for the differential...Ch. 9.2 - Prob. 11ECh. 9.2 - Prob. 12ECh. 9.2 - Prob. 13ECh. 9.2 - Prob. 14ECh. 9.2 - (a) Use Eulers method with each of the following...Ch. 9.2 - A direction field for a differential equation is...Ch. 9.2 - Use Eulers method with step size 0.5 to compute...Ch. 9.2 - Prob. 22ECh. 9.2 - Prob. 23ECh. 9.2 - (a) Use Eulers method with step size 0.2 to...Ch. 9.2 - The figure shows a circuit containing an...Ch. 9.3 - Solve the differential equation. 1. dydx=3x2y2Ch. 9.3 - Solve the differential equation. 2. dydx=xy4Ch. 9.3 - Solve the differential equation. 2. dydx=xyCh. 9.3 - Solve the differential equation. 4. xy=y+3Ch. 9.3 - Solve the differential equation. 3. xyy=x2+1Ch. 9.3 - Solve the differential equation. 4. y+xey=0Ch. 9.3 - Solve the differential equation. 5. (ey1)y=2+cosxCh. 9.3 - Solve the differential equation. 8. dydx=2xy2+1Ch. 9.3 - Solve the differential equation. 9. dpdt=t2pp+t21Ch. 9.3 - Solve the differential equation. 10. dzdt+et+z=0Ch. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Prob. 15ECh. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Find the solution of the differential equation...Ch. 9.3 - Find an equation of the curve that passes through...Ch. 9.3 - Find the function f such that f(x) = xf(x) x and...Ch. 9.3 - Solve the differential equation y = x + y by...Ch. 9.3 - Solve the differential equation xy = y + xey/x by...Ch. 9.3 - (a) Solve the differential equation y=2x1y2. (b)...Ch. 9.3 - Solve the equation eyy + cos x = 0 and graph...Ch. 9.3 - Find the orthogonal trajectories of the family of...Ch. 9.3 - Find the orthogonal trajectories of the family of...Ch. 9.3 - Find the orthogonal trajectories of the family of...Ch. 9.3 - Find the orthogonal trajectories of the family of...Ch. 9.3 - Find a function f such that f(3) = 2 and (t2 +...Ch. 9.3 - Solve the initial-value problem in Exercise 9.2.27...Ch. 9.3 - In Exercise 9.2.28 we discussed a differential...Ch. 9.3 - In an elementary chemical reaction, single...Ch. 9.3 - A sphere with radius 1 m has temperature 15C. It...Ch. 9.3 - A glucose solution is administered intravenously...Ch. 9.3 - A certain small country has 10 billion in paper...Ch. 9.3 - A tank contains 1000 L of brine with 15 kg of...Ch. 9.3 - The air in a room with volume 180 m3 contains...Ch. 9.3 - A vat with 500 gallons of beer contains 4% alcohol...Ch. 9.3 - A tank contains 1000 L of pure water. Brine that...Ch. 9.3 - An object of mass m is moving horizontally through...Ch. 9.3 - A model for tumor growth is given by the Gompertz...Ch. 9.3 - Prob. 1APCh. 9.3 - Prob. 2APCh. 9.4 - A population grows according to the given logistic...Ch. 9.4 - A population grows according to the given logistic...Ch. 9.4 - The Pacific halibut fishery has been modeled by...Ch. 9.4 - Suppose a population P(t) satisfies...Ch. 9.4 - Suppose a population grows according to a logistic...Ch. 9.4 - The population of the world was about 6.1 billion...Ch. 9.4 - Prob. 10ECh. 9.4 - Prob. 11ECh. 9.4 - Biologists stocked a lake with 400 fish and...Ch. 9.4 - (a) Show that if P satisfies the logistic equation...Ch. 9.4 - For a fixed value of M (say M = 10), the family of...Ch. 9.4 - Consider a population P = P(t) with constant...Ch. 9.4 - Prob. 21ECh. 9.4 - In a seasonal-growth model, a periodic function of...Ch. 9.4 - Prob. 24ECh. 9.4 - Prob. 25ECh. 9.5 - Determine whether the differential equation is...Ch. 9.5 - Determine whether the differential equation is...Ch. 9.5 - Determine whether the differential equation is...Ch. 9.5 - Determine whether the differential equation is...Ch. 9.5 - Solve the differential equation. 5. y' + y = 1Ch. 9.5 - Solve the differential equation. 6. y' y = exCh. 9.5 - Solve the differential equation. 7. y' = x yCh. 9.5 - Solve the differential equation. 8. 4x3y + x4y' =...Ch. 9.5 - Solve the differential equation. 9. xy+y=xCh. 9.5 - Solve the differential equation. 10. 2xy+y=2xCh. 9.5 - Solve the differential equation. 11. xy2y=x2,x0Ch. 9.5 - Solve the differential equation. 12. y3x2y=x2Ch. 9.5 - Solve the differential equation. 13....Ch. 9.5 - Solve the differential equation. 14....Ch. 9.5 - Solve the differential equation. 15. y+ycosx=xCh. 9.5 - Solve the differential equation. 16. y+2xy=x3ex2Ch. 9.5 - Solve the initial-value problem. 17....Ch. 9.5 - Solve the initial-value problem. 18....Ch. 9.5 - Solve the initial-value problem. 15....Ch. 9.5 - Solve the initial-value problem. 16....Ch. 9.5 - Solve the initial-value problem. 17....Ch. 9.5 - Solve the initial-value problem. 18....Ch. 9.5 - Solve the initial-value problem. 19....Ch. 9.5 - Solve the initial-value problem. 20....Ch. 9.5 - Solve the differential equation and use a...Ch. 9.5 - Prob. 26ECh. 9.5 - Bernoulli Differential Equations A Bernoulli...Ch. 9.5 - Bernoulli Differential Equations A Bernoulli...Ch. 9.5 - Bernoulli Differential Equations A Bernoulli...Ch. 9.5 - Solve the second-order equation xy" + 2y' = 12x2...Ch. 9.5 - Prob. 31ECh. 9.5 - Prob. 32ECh. 9.5 - The figure shows a circuit containing an...Ch. 9.5 - Prob. 34ECh. 9.5 - Prob. 35ECh. 9.5 - A tank with a capacity of 400 L is full of a...Ch. 9.5 - An object with mass m is dropped from rest and we...Ch. 9.5 - Prob. 40ECh. 9.5 - Show that the substitution z = 1/P transforms the...Ch. 9.5 - Prob. 42ECh. 9.6 - For each predator-prey system, determine which of...Ch. 9.6 - Each system of differential equations is a model...Ch. 9.6 - The system of differential equations...Ch. 9.6 - Prob. 4ECh. 9.6 - Prob. 5ECh. 9.6 - Prob. 6ECh. 9.6 - Prob. 7ECh. 9.6 - Graphs of populations of two species are shown....Ch. 9.6 - Populations of aphids and ladybugs are modeled by...Ch. 9.6 - Prob. 11ECh. 9 - (a) What is a differential equation? (b) What is...Ch. 9 - What can you say about the solutions of the...Ch. 9 - What is a direction field for the differential...Ch. 9 - Explain how Euler's method works.Ch. 9 - What is a separable differential equation? How do...Ch. 9 - What is a first-order linear differential...Ch. 9 - (a) Write a differential equation that expresses...Ch. 9 - (a) Write the logistic differential equation. (b)...Ch. 9 - (a) Write Lotka-Volterra equations to model...Ch. 9 - Determine whether the statement is true or false....Ch. 9 - Determine whether the statement is true or false....Ch. 9 - Determine whether the statement is true or false....Ch. 9 - Determine whether the statement is true or false....Ch. 9 - Determine whether the statement is true or false....Ch. 9 - Prob. 7TFQCh. 9 - Determine whether the statement is true or false....Ch. 9 - (a) A direction field for the differential...Ch. 9 - (a) Sketch a direction field for the differential...Ch. 9 - (a) A direction field for the differential...Ch. 9 - (a) Use Euler's method with step size 0.2 to...Ch. 9 - Solve the differential equation. 5. y=xesinxycosxCh. 9 - Solve the differential equation. 6. dxdy=1t+xtxCh. 9 - Solve the differential equation. 7. 2yey2y=2x+3xCh. 9 - Solve the differential equation. 8. x2yy=2x3e1/xCh. 9 - Solve the initial-value problem. 9....Ch. 9 - Solve the initial-value problem. 10. (1 + cos x)...Ch. 9 - Solve the initial-value problem. 11. xy' y = x ln...Ch. 9 - Solve the initial-value problem y' = 3x2ey, y(0) =...Ch. 9 - Find the orthogonal trajectories of the family of...Ch. 9 - Find the orthogonal trajectories of the family of...Ch. 9 - (a) Write the solution of the initial-value...Ch. 9 - The von Bertalanffy growth model is used to...Ch. 9 - A tank contains 100 L of pure water. Brine that...Ch. 9 - One model for the spread of an epidemic is that...Ch. 9 - The Brentano-Stevens Law in psychology models the...Ch. 9 - The transport of a substance across a capillary...Ch. 9 - Populations of birds and insects are modeled by...Ch. 9 - Suppose the model of Exercise 22 is replaced by...Ch. 9 - Barbara weighs 60 kg and is on a diet of 1600...Ch. 9 - Find all functions f such that f' is continuous...Ch. 9 - A student forgot the Product Rule for...Ch. 9 - Let f be a function with the property that f(0) =...Ch. 9 - Find all functions f that satisfy the equation...Ch. 9 - Find the curve y = f(x) such that f(x) 0, f(0) =...Ch. 9 - A subtangent is a portion of the x-axis that lies...Ch. 9 - A peach pie is taken out of the oven at 5:00 pm....Ch. 9 - Snow began to fall during the morning of February...Ch. 9 - (a) Suppose that the dog in Problem 9 runs twice...Ch. 9 - A planning engineer for a new alum plant must...Ch. 9 - Find the curve that passes through the point (3,...Ch. 9 - Recall that the normal line to a curve at a point...Ch. 9 - Find all curves with the properly that if the...Ch. 9 - Find all curves with the property that if a line...
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