First and Second order DE, Exercises of Calculus for Engineers

many problems for practicing first and second-order DE

Typology: Exercises

2020/2021

Uploaded on 02/13/2022

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Problem Set 1 First order DE (Do at least 5 problems of each type)
1) ๐‘ฆโ€ฒ= ๐‘ฆ โˆ’ ๐‘ฅ, ๐‘ฆ(0)= 1/3
2) ๐‘ฆโ€ฒ= ๐‘ฆ4/5, ๐‘ฆ(0)= 1
3) ๐‘ฆโ€ฒ=๐‘ฅ๐‘ฆ
๐‘ฅ2+4
4) 3๐‘ฅ๐‘ฆโ€ฒโˆ’ 1 = ln ๐‘ฅ + ๐‘ฆ, ๐‘ฆ(1)= 2
5) ๐‘ฆโ€ฒ=1โˆ’2๐‘ฆโˆ’4๐‘ฅ
1+๐‘ฆ+2๐‘ฅ by using ๐‘ฆ + 2๐‘ฅ = ๐‘ฃ
6) ๐‘ฅ3๐‘ฆโ€ฒ + 3๐‘ฅ2๐‘ฆ = 1/๐‘ฅ
7) ๐‘ฆโ€ฒ= ๐‘ฆ + ๐‘ฆ2, ๐‘ฆ(0)= 0
8) ๐‘ฆโ€ฒ = 2(๐‘ฆ โˆ’ 1)tanh 2๐‘ฅ , ๐‘ฆ(0)= 4
9) Show that ๐‘ฆ = ๐‘๐‘’๐‘ฅ+ ๐‘ฅ + 1 is the solution to ๐‘ฆโ€ฒ= ๐‘ฆ โˆ’ ๐‘ฅ when ๐‘ฆ(0)= 3
10) ๐‘ฆโ€ฒ๐‘ฅ ๐‘™๐‘› ๐‘ฅ = ๐‘ฆ, ๐‘ฆ(3)=ln 81
11) 2๐‘ฆ๐‘ฆโ€ฒ+ ๐‘ฆ2sin ๐‘ฅ = sin ๐‘ฅ, ๐‘ฆ(0)=โˆš2
12) ๐‘ฆโ€ฒ+ 2๐‘ฆ = ๐‘ก2โˆ’ ๐‘ก + 1, ๐‘ฆ(1)= 1
2
13) ๐‘ฆโ€ฒ=๐‘ฅ๐‘ฆ3
โˆš1+๐‘ฅ2
14) ๐‘‘๐‘Ÿ
๐‘‘๐œƒ = โˆ’๐‘Ÿ tan ๐œƒ
15) ๐‘‘๐‘ฆ
๐‘‘๐‘ฅ =๐‘ฅ(๐‘’๐‘ฅ2+2)
6๐‘ฆ2; ๐‘ฆ(0)= 1
16) ๐‘‘๐‘ฆ
๐‘‘๐‘ฅ = 2๐‘ฅ(๐‘ฆ โˆ’ 5)
17) ๐‘‘๐‘ฆ
๐‘‘๐‘ฅ = (1 + ๐‘’โˆ’๐‘ฅ)(๐‘ฆ2โˆ’ 1)
18) sin ๐‘ฅ ๐‘‘๐‘ฆ
๐‘‘๐‘ฅ + ๐‘ฆ cos ๐‘ฅ = sin ๐‘ฅ
19) ๐‘ฅ๐‘ฆโ€ฒ+ ๐‘ฆ = ๐‘ฅ2+ 1
20) ๐‘‘๐‘ฆ
๐‘‘๐‘ฅ + 2๐‘ฆ = cos ๐‘ฅ
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Problem Set 1 First order DE (Do at least 5 problems of each type)

โ€ฒ

โ€ฒ

4 / 5

โ€ฒ

๐‘ฅ๐‘ฆ

๐‘ฅ

2

  • 4

โ€ฒ

โˆ’ 1 = ln ๐‘ฅ + ๐‘ฆ, ๐‘ฆ( 1 ) = 2

โ€ฒ

1 โˆ’ 2 ๐‘ฆโˆ’ 4 ๐‘ฅ

1 +๐‘ฆ+ 2 ๐‘ฅ

by using ๐‘ฆ + 2 ๐‘ฅ = ๐‘ฃ

3

2

โ€ฒ

2

  1. ๐‘ฆโ€ฒ = 2 (๐‘ฆ โˆ’ 1 ) tanh 2 ๐‘ฅ , ๐‘ฆ( 0 ) = 4

  2. Show that ๐‘ฆ = ๐‘๐‘’

๐‘ฅ

  • ๐‘ฅ + 1 is the solution to ๐‘ฆ

โ€ฒ

= ๐‘ฆ โˆ’ ๐‘ฅ when ๐‘ฆ( 0 ) = 3

โ€ฒ

= ln 81

โ€ฒ

2

sin ๐‘ฅ = sin ๐‘ฅ, ๐‘ฆ( 0 ) = โˆš

โ€ฒ

2

1

2

โ€ฒ

๐‘ฅ๐‘ฆ

3

โˆš 1 +๐‘ฅ

2

๐‘‘๐‘Ÿ

๐‘‘๐œƒ

= โˆ’๐‘Ÿ tan ๐œƒ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

๐‘ฅ(๐‘’

๐‘ฅ

2

  • 2 )

6 ๐‘ฆ

2

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

โˆ’๐‘ฅ

2

  1. sin ๐‘ฅ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

  • ๐‘ฆ cos ๐‘ฅ = sin ๐‘ฅ

โ€ฒ

2

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

  • 2 ๐‘ฆ = cos ๐‘ฅ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

6

๐‘ฅ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

๐‘ฅ+ 1

8 + 2 ๐œ‹ sin(๐œ‹๐‘ฆ)

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

๐‘ฅ

๐‘ฆโˆ’ 3

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

1

๐‘ฅ

โ€ฒ

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

  • cot ๐‘ฅ ๐‘ฆ = cos ๐‘ฅ

2

๐‘‘๐‘ฆ

๐‘‘๐‘ฅ

โ€ฒโ€ฒ

โ€ฒ

โˆ’ 2 ๐‘ก

โ€ฒ

โ€ฒโ€ฒ

โ€ฒ

โ€ฒ

  1. Guess the form of ๐‘ฆ

๐‘

for the following problems

a) ๐‘ฆ

โ€ฒโ€ฒ

โˆ’ 4 ๐‘ฅ

b) 2 ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

โˆ’๐‘ฅ

c) 4 ๐‘ฆ

โ€ฒโ€ฒ

  • ๐‘ฆ = cos

1

2

d) ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

2

e) ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

๐‘ฅ

sin ๐‘ฅ

  1. Guess the form of ๐‘ฆ

๐‘

for the following problems

a) ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

โˆ’ 5 ๐‘ฅ

b) 3 ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

  • 3 ๐‘ฆ = 9 ๐‘ฅ + 5 cos ๐‘ฅ

c) ๐‘ฆ

โ€ฒโ€ฒ

โ€ฒ

  • 16 ๐‘ฆ = 64 cosh 4 ๐‘ฅ

d) y y t e t t e t

t t

3 12 1 5 sin 2 cos 2 4 sin 2

โˆ’ 2 โˆ’ 2

  • = โˆ’ + +

๏‚ข๏‚ข

e) y y y t te t t

t

4 16 5 2 cos 8 sin 2

2 4

๏‚ข๏‚ขโˆ’ ๏‚ข+ = + + โˆ’

f) y y y e te t t e t

t t t

3 11 10 10 14 cos 9 sin 2

โˆ’ 6 โˆ’ 5 โˆ’ 4

  • = โˆ’ + โˆ’

๏‚ข

๏‚ข๏‚ข