precal
posted by stellar .
Find all solutions of the given equation. (Enter your answers as a commaseparated list. Let k be any integer. Round terms to two decimal places where appropriate.)
2 cos θ − 1 = 0

solve for cosθ the way you would for any other variable.
2cosθ = 1
cos θ = 1/2
ta da. Of course, now you have to now how to find θ, but that's no problem, right? 
Find the real solutions of the equation. (Round your answers to three decimal places. Enter your answers as a commaseparated list.)
3.4x4 − 1.9x2 = 2.2