I just started a class called advanced engineering mathmatics and I guess that includes trigonometry from highschool. If anyone could help that would be great because I haven't done this stuff in years. Here are the problems:

Solve for x:

18cos^2x + 3cosx - 1 = 0

cosx + 3sinx = 1

13^(3x) * 4^(2x) = 5

Thanks for any help in advance, this wouldn't be a problem if the book wasn't sold out at the bookstore.