j j
SOLUTION MANUAL
j
, TableofContents j j
Part I OrdinaryDifferentialEquations
j j j
1 Introduction to Differential Equations
j j j 1
2 First-Order Differential Equations
j j 22
3 Higher-Order Differential Equations j j 99
4 The Laplace Transform
j j 198
5 Series Solutions of Linear Differential Equations
j j j j j 252
6 Numerical Solutions of Ordinary Differential Equations
j j j j j 317
Part II Vectors,Matrices,andVectorCalculus
j j j j j
7 Vectors 339
8 Matrices 373
9 Vector Calculus
j 438
Part III SystemsofDifferentialEquations
j j j j
10 Systems of Linear Differential Equations
j j j j 551
11 Systems of Nonlinear Differential Equations
j j j j 604
Part IV FourierSeriesandPartialDifferentialEquations
j j j j j j
12 Orthogonal Functions and Fourier Series
j j j j 634
13 Boundary-Value Problems in Rectangular Coordinates j j j j 680
14 Boundary-Value Problems in Other Coordinate Systems j j j j j 755
15 Integral Transform Method
j j 793
16 Numerical Solutions of Partial Differential Equations
j j j j j 832
, Part V Complex Analysis
j j j
17 Functions of a Complex Variablej j j j 854
18 Integration in the Complex Plane j j j j 877
19 Series and Residues
j j 896
20 Conformal Mappings j 919
Appendices
Appendix II Gamma function
j j 942
Projects
3.7 Road Mirages j 944
3.10 The Ballistic Pendulum
j j 946
8.1 Two-Ports in Electrical Circuits j j j 947
8.2 Traffic Flow j 948
8.15 Temperature Dependence of Resistivity j j j 949
9.16 Minimal Surfaces j 950
14.3 The Hydrogen Atom
j j 952
15.4 The Uncertainity Inequality in Signal Processing
j j j j j 955
15.4 Fraunhofer Diffraction by a Circular Aperture
j j j j j 958
16.2 Instabilities of Numerical Methods j j j 960
, Part I j OrdinaryDifferentialEquations
j j
Introduction to Differenti
1 alEquationsj
j j
EXERCISES1.1 j
j Definitions and Terminology
j j
1. Secondjorder;jlinear
2. Thirdjorder;jnonlinearjbecausejofj(dy/dx)4
3. Fourthjorder;jlinear
4. Secondjorder;jnonlinearjbecausejofjcos(rj+ju)
!
5. Secondjorder;jnonlinearj becausejofj(dy/dx)2jor 1 + j (dy/dx)2
6. Secondj order;j nonlinearj becausej ofjR2
7. Thirdjorder;jlinear
8. Secondj order;j nonlinearj becausej ofjx˙2
9. Writingjthejdifferential jequationjinjthejformjx(dy/dx)j+jy2j=j1,jwejseejthatjitjisjnonlinearjinjyjbecausejofjy2.jHow
ever,jwritingjitjinjthejformj(y2j−j1)(dx/dy)j+jxj=j0,jwejseejthatjitjisjlinearjinjx.
10. Writingjthejdifferential jequationjinjthejformju(dv/du)j+j(1j+ju)vj=jueuj wejseejthatjitjisjlinearjinjv.j However,jwriti
ngjitjinjthejformj(vj+juvj−jueu)(du/dv)j+juj=j0,jwejseejthatjitjisjnonlinearjinju.
11. Fromjyj=je−x/2jwejobtainjy′j=j−j1je2−x/2.j Thenj2y′j+jyj=j−e−x/2j+je−x/2j=j0.
12. Fromjyj=j 6j−j 6je−20tj wejobtainjdy/dtj=j24e−20t,jsojthat
5 5
"j #
dy +j20yj =j 24e −20t 6 6 −20t
+j 20 −j e =j 24.
dt 5j 5 j
13. Fromj yj =j e3xjcosj2xj wej obtainj y′j =j 3e3xjcosj2xj −j 2e3xjsinj2xj andj y′′j =j 5e3xjcosj2xj −j 12e3xjsinj2x,j soj that
y′′j −j6y′j +j13yj =j0.
14. Fromj yj =j−jcosjxjln(secjxj+jtanjx)j wej obtainj y′j =j−1j+jsinjxjln(secjxj+jtanjx)j and
y′′j=jtanjxj+jcosjxjln(secjxj+jtanjx).j Thenjy′′j+jyj=jtanjx.
15. Thejdomainjofjthejfunction,jfoundjbyjsolvingjxj+j2j≥j0,jisj[−2,j∞).j Fromjy′j =j1j+j2(xj+j2)−1/2jwejhave
—1/2
(yj− x)y′ =j(yj− x)[1j +j (2(xj +j 2) ]
—1/2
=jyj−jxj+j2(yj− x)(xj +j 2)
—1/2
=jyj−jxj+j2[xj+j4(xj+j2)1/2j− x](xj +j 2)
=jyj−jxj+j8(xj+j2)1/2(xj+j2)−1/2j=jyj−jxj+j8.
1