In applications, most initial value problems will have a unique solution. In fact, the existence of unique solutions is so important that there is a theorem about the existence and uniqueness of a solution. Consider the initial value problem =f(x,y). y(x) =yo. Iff and dx af dy are continuous functions in some rectangle R={(x,y):a

Algebra & Trigonometry with Analytic Geometry
13th Edition
ISBN:9781133382119
Author:Swokowski
Publisher:Swokowski
Chapter7: Analytic Trigonometry
Section7.6: The Inverse Trigonometric Functions
Problem 91E
icon
Related questions
Question
In applications, most initial value problems will have a unique solution. In fact, the existence of unique solutions is so important that there is a theorem about the existence and uniqueness of a solution. Consider the initial value problem
af
are continuous functions in some rectangle R = {(x,y):a<x<b, c<y<d} that contains the point (Xo Yo), then the initial value problem has a unique solution (x) in some interval xo -8<x<x+8, where is a positive number. The method for separable equations
ду
dy 3
can give a solution, but it may not give all the solutions. To illustrate this, consider the equation =y
dx
1
dy
3
(a) Use the method of separation of variables to find the solution to =y
Begin by separating the variables.
dx
dy=dx
Solve the differential equation, ignoring lost solutions, if any.
dy
nie by
(b) Show that the initial value problemy with y(0)=0 is satisfied for C =0 by y=
For y = 0, y(0)=
Now, determine
of
ду
Using the general solution, substituting for x and for y(x) implies that C=. So, the solution
x>0, satisfies the initial value problem =y with y(0) = 0.
dy
dx
(c) Now show that the constant function y = 0 also satisfies the initial value problem given in part (b). Hence, this initial value problem does not have a unique solution.
=
dy
dx
1
3
dy
dx
(d) Finally, show that the conditions for the theorem are not satisfied for the initial value problem in part (b). Begin by identifying f(x,y) in the initial value problem in (b).
f(x,y)=
af
ду
=
Answer parts (a) through (d).
for x ≥ 0.
, and y
C
1
1
3
dy
Thus, it holds that the constant function y = 0 satisfies the initial value problem -= y³ with y(0) = 0.
dx
=f(x,y). y (xo) yo. Iff and
dx
Transcribed Image Text:In applications, most initial value problems will have a unique solution. In fact, the existence of unique solutions is so important that there is a theorem about the existence and uniqueness of a solution. Consider the initial value problem af are continuous functions in some rectangle R = {(x,y):a<x<b, c<y<d} that contains the point (Xo Yo), then the initial value problem has a unique solution (x) in some interval xo -8<x<x+8, where is a positive number. The method for separable equations ду dy 3 can give a solution, but it may not give all the solutions. To illustrate this, consider the equation =y dx 1 dy 3 (a) Use the method of separation of variables to find the solution to =y Begin by separating the variables. dx dy=dx Solve the differential equation, ignoring lost solutions, if any. dy nie by (b) Show that the initial value problemy with y(0)=0 is satisfied for C =0 by y= For y = 0, y(0)= Now, determine of ду Using the general solution, substituting for x and for y(x) implies that C=. So, the solution x>0, satisfies the initial value problem =y with y(0) = 0. dy dx (c) Now show that the constant function y = 0 also satisfies the initial value problem given in part (b). Hence, this initial value problem does not have a unique solution. = dy dx 1 3 dy dx (d) Finally, show that the conditions for the theorem are not satisfied for the initial value problem in part (b). Begin by identifying f(x,y) in the initial value problem in (b). f(x,y)= af ду = Answer parts (a) through (d). for x ≥ 0. , and y C 1 1 3 dy Thus, it holds that the constant function y = 0 satisfies the initial value problem -= y³ with y(0) = 0. dx =f(x,y). y (xo) yo. Iff and dx
Expert Solution
steps

Step by step

Solved in 4 steps with 4 images

Blurred answer
Recommended textbooks for you
Algebra & Trigonometry with Analytic Geometry
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:
9781133382119
Author:
Swokowski
Publisher:
Cengage
Calculus For The Life Sciences
Calculus For The Life Sciences
Calculus
ISBN:
9780321964038
Author:
GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:
Pearson Addison Wesley,