4 Chapter 9, First order linear equations and the integrating factor. Exercises page 86

4.1 problem 9.1 (i)
4.2 problem 9.1 (ii)
4.3 problem 9.1 (iii)
4.4 problem 9.1 (iv)
4.5 problem 9.1 (v)
4.6 problem 9.1 (vi)
4.7 problem 9.1 (vii)
4.8 problem 9.1 (viii)
4.9 problem 9.4