12 Chapter 2. Second-Order Linear Equations. Section 2.4. THE USE OF A KNOWN SOLUTION TO FIND ANOTHER. Page 74

 12.1 problem 1(a)
 12.2 problem 1(b)
 12.3 problem 2
 12.4 problem 3
 12.5 problem 4
 12.6 problem 5
 12.7 problem 6(a)
 12.8 problem 6(b)
 12.9 problem 6(c)
 12.10 problem 7
 12.11 problem 8