Find a general solution in terms of exponentials for each differential equation. 1. u" – u' – 6u = 0 2 u"-9u=0 3. u"+9u=0 4. 4u" +u=0 5. u" — 4u' +4u = 0 6 u" +4u' +4u = 0 7. u"-4u4u = 0 & u" +4u' – 4u = 0 9. u"-4u = 0 10. u"-4u' + 8u = 0 11. u″ +2u' + 10u = 0 12. 2u" +6u' + 5u = 0 Write a general solution, in the form of Eq. 1.6.9 or 1.6.13, for each equation. 13. u" - u'-6u = 0 14. u"-9u = 0 15. u" +9u=0 16. 4u" +u= 0 17. u"-4u' - 4u = 0 18. u" +4u' − 4u = 0 19. u"-4u = 0