How do you solve #2cos^2x+3cosx=-1#?
1 Answer
Apr 14, 2017
Explanation:
For simplicity, we let
And you'll notice that we can split the middle term and factorize
And now it becomes obvious (by a process formally known as Null Factor Theorem) that:
Solving for each one:
And if you solve the above using your calculator, you get #x=-30^o
As for the other case:
And using a calculator you get: