g g
SOLUTION MANUAL
g
, TableofContents g g
Part I OrdinaryDifferentialEquations
g g g
1 Introduction to Differential Equations g g g 1
2 First-Order Differential Equations
g g 22
3 Higher-Order Differential Equations g g 99
4 The Laplace Transform
g g 198
5 Series Solutions of Linear Differential Equations
g g g g g 252
6 Numerical Solutions of Ordinary Differential Equations
g g g g g 317
Part II Vectors,Matrices,andVector Calculus
g g g g g
7 Vectors 339
8 Matrices 373
9 Vector Calculus
g 438
Part III Systems of DifferentialEquations
g g g g
10 Systems of Linear Differential Equations
g g g g 551
11 Systems of Nonlinear Differential Equations
g g g g 604
Part IV FourierSeries andPartialDifferentialEquations
g g g g g g
12 Orthogonal Functions and Fourier Series
g g g g 634
13 Boundary-Value Problems in Rectangular Coordinates g g g g 680
14 Boundary-Value Problems in Other Coordinate Systems g g g g g 755
15 Integral Transform Method
g g 793
16 Numerical Solutions of Partial Differential Equations
g g g g g 832
, Part V Complex Analysis
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17 Functions of a Complex Variableg g g g 854
18 Integration in the Complex Plane g g g g 877
19 Series and Residues
g g 896
20 Conformal Mappings g 919
Appendices
Appendix II Gamma function
g g 942
Projects
3.7 Road Mirages g 944
3.10 The Ballistic Pendulum
g g 946
8.1 Two-Ports in Electrical Circuits g g g 947
8.2 Traffic Flow g 948
8.15 Temperature Dependence of Resistivity g g g 949
9.16 Minimal Surfaces g 950
14.3 The Hydrogen Atom
g g 952
15.4 The Uncertainity Inequality in Signal Processing
g g g g g 955
15.4 Fraunhofer Diffraction by a Circular Apertureg g g g g 958
16.2 Instabilities of Numerical Methods g g g 960
, Part I g OrdinaryDifferentialEquations g g
Introduction to
1 DifferentialEquations g
g
g
EXERCISES 1.1 g
g Definitions and Terminology g g
1. Second order; linear g g
2. Third order; nonlinear because of (dy/dx)4
g g g g g
3. Fourth order; linear g g
4. Second order; nonlinear because of cos(r + u)
g g g g g g g
!
5. Second order; nonlinear because of (dy/dx)2 or
g g g g g g 1 + (dy/dx)2 g
6. Second g order; g nonlinear g because g of gR2
7. Third order; linear
g g
8. Second order; nonlinear because of x˙2
g g g g g
9. Writing the differential equation in the form x(dy/dx) + y2 = 1, we see that it is nonlinear in y because of y2.
g g g g g g g g g g g g g g g g g g g g g g
g However, gwriting g it gin gthe g form g (y g− g1)(dx/dy) g+ gx g= g 0, g we g see gthat git g is glinear gin g x.
2
10. Writing the differential equation in the form u(dv/du) + (1 + u)v = ueu we see that it is linear in v. However,
g g g g g g g g g g g g g g g g g g g g g g
writing it in the form (v + uv − ueu)(du/dv) + u = 0, we see that it is nonlinear in u.
g g g g g g g g g g g g g g g g g g g g g g
11. From gyg=ge−x/2 gwe gobtain gy′ g= g−g1ge−x/2. g Then g2y′ g+ gy g= g−e−x/2g+ ge−x/2g= g0.
2
12. From y = 6 − 6 e−20t we obtain dy/dt = 24e−20t, so that
g g g g g
g
g g g g g g g
5 5
" # g
dy + 20y = −20t 6 6 −20t
+ − e = 24. g g
24e g g
20 5 5 g
g
g g
dt
13. From y = e3x cos 2x we obtain y′ = 3e3x cos 2x − 2e3x sin 2x and y′′ = 5e3x cos 2x − 12e3x sin 2x, so that
g g g g g g g g g g g g g g g g g g g g g g g g g g g g
y′′ − 6y′ + 13y = 0.
g g g g g g
14. From y = − cos x ln(sec x + tan x) we obtain y′ = −1 + sin x ln(sec x + tan x) and
g g g g g g g g g g g g g g g g g g g g g g g g
y′′ = tan x + cos x ln(sec x + tan x). Then y′′ + y = tan x.
g g g g g g g g g g g g g g g g g g
15. The domain of the function, found by solving x + 2 ≥ 0, is [−2, ∞). From y′ = 1 + 2(x + 2)−1/2 we have
g g g g g g g g g g g g g g g g g g g g g g g g g
—1/2
(y − x)y′ = (y − x)[1 + (2(x + 2)
g g g g g g g ]
—1/2
= y − x + 2(y − x)(x + 2)
g g g g g g g g
—1/2
= y − x + 2[x + 4(x + 2)1/2 −
g g g g g g g g g g x](x + 2) g g
= y − x + 8(x + 2)1/2(x + 2)−1/2 = y − x + 8.
g g g g g g g g g g g g g g g
1