University of Memphis

Dept Math Sciences

MATH 2120 – Differential Equations

Spring 2023

Dwiggins

**Test # 2**, scheduled for Monday, March 27,

will cover material from Chapters Four, Five, and Seven.

**Homework Assignment # 4** (Solutions)

Review Exercises from Chapter Seven:

- Section 7.1 (page 280), # 13-25 odd (Laplace Transforms)
- Section 7.2 (pages 288-9), # 1-19 odd (Finding Inverse Transforms)
- Section 7.2 (page 289), # 31-37 odd (Using Transforms to Solve IVP's)
- Section 7.3 (page 298), # 21-29 odd (Equations with Repeated Roots)
- Section 7.6 (page 319), # 1-15 odd (Linear Systems of Equations)

Review Exercises from Chapter Five:

- Section 5.1 (pages 205-7), # 1-9 odd, # 23, # 24, # 31-34 all (Spring-Mass Systems)
- Section 5.1 (page 209), # 45-49 odd, # 53, # 57, # 58 (RLC Circuits)
- Note: It may be easier to use Laplace Transforms to do some of the problems listed above.

**Homework Assignment # 3** (Solutions)

Practice Exercises from Chapter Four:

- Section 4.1 (pages 127-8), # 1-19 odd (Second Order and Higher-Ordered Equations)
- Section 4.2 (pages 131-2), # 1-19 odd (Reduction of Order)
- Section 4.3 (pages 137-8), # 1-17 odd, # 29-37 odd (Constant Coefficient Equations)
- Section 4.4 (page 147), # 1-15 odd, # 27, # 29, #31 (Method of Undetermined Coefficients)
- Section 4.5 (pages 155-6), # 1-5 odd, # 15-25 odd, # 27-33 odd,

# 51, #53, # 55 (Undetermined Coefficients, Annihilator Method) - Section 4.6 (pages 161-2), # 1-9 odd, # 19, # 21, # 23 (Variation of Parameters)
- Section 4.7 (page 168), # 1-23 odd (skip # 17) (Euler Equations)

**Homework Assignment # 2** (Solutions)

Practice Exercises from Chapter Two:

- Section 2.1 (page 44), # 15, 21, 23, 25
- Section 2.2 (page 51), # 7-17 odd
- Section 2.3 (pages 60-61), # 3-13 odd, # 25-31 odd
- Section 2.4 (page 69), # 1-13 odd, # 21, 27, 29, 31
- Section 2.5 (page 74), # 1-25 odd

**Homework Assignment # 1** (Solutions)

Practice Exercises from Chapter One:

- Section 1.1 (page 10), # 1-17 odd
- Section 1.2 (page 18), # 7-21 odd
- Chapter Review (page 34), # 17, 19, 23, 25, 27, 31, 33