University of Bahrain
College of Science
Department of Mathematics
First Semester 2018/2019
Maths-205 Final Exam
Date: January 10, 2019
Time: 2 hour (11:30-13:30) Max. Marks: 40
Student Name:
Serial No:
Student Number: Section:
Please check that this test consists of 8 questions.
Show your work clearly.
Calculator is not allowed
Questions 1 2 3 4 5 6 7 8 Total
Max. 5 5 5 5 6 6 8 5 45
Marks
Marks
obtained
1
Question 1. solve the differential equation
𝑥 3 𝑦 ′′′ − 𝑥 2 𝑦 ′′ + 2𝑥𝑦 ′ − 2𝑦 = 0 , 𝑥 > 0 [5]
2
−𝑥 2
Question 2. Given that 𝑦1 = − is a solution to 𝑦 ′′ + 2𝑦 ′ − 3𝑦 = 𝑥
3 9
𝑒 2𝑥
and 𝑦2 = is a solution to 𝑦 ′′ + 2𝑦 ′ − 3𝑦 = 𝑒 2𝑥 . Find the
5
general solution to 𝑦 ′′ + 2𝑦 ′ − 3𝑦 = 4𝑥 − 5𝑒 2𝑥
[5]
3
Question 3. Solve the DE
4𝑥𝑦𝑦 ′ = 2𝑦 2 − 𝑥2 [5]
4
Question 4. Find the general solution of differential equation.
𝑦 ′′′′ + 𝑦 ′′′ − 7𝑦 ′′ − 𝑦′ + 6𝑦 = 0 [5]
5
Question 5. Solve Initial Value problem (IVP) using Laplace transform
𝑦" − 2𝑦′ + 5𝑦 = −8𝑒 −𝑡 , 𝑦(0) = 2, 𝑦′ (0) = 12 [6]
6
Question 6. Solve using Laplace transform
𝑥 ′ (𝑡) = 𝑥 − 𝑦, 𝑥(0) = −1 ,
𝑦 ′ (𝑡) = 2𝑥 + 4𝑦, 𝑦(0) = 0 [6]
7
Question 7. Using the method of variation of parameter find the general solution of
𝑥 2 𝑦" + 𝑥𝑦′ − 𝑦 = 𝑥 𝑙𝑛𝑥, ( 𝑥 > 0) [8]
8
Question 8. Let 𝑦1 and 𝑦2 be the solution of the differential equation
𝑦" + 𝑎(𝑥)𝑦 = 0 (1).
Show that 𝑍 = 𝑦1𝑦2 solution for differential equation.
𝑍 ′′′ + 4𝑎(𝑥 )𝑍 ′ + 2𝑎′ (𝑥 )𝑍 = 0 (2)
(Bonus, 5 marks)