Thread: Solve for X:

Solve for X:


3cos(x) + 3 = -2cos^2(x), for x E [-pi, 3pi]

Originally Posted by Mr_Green

Solve for X:


3cos(x) + 3 = -2cos^2(x), for x E [-pi, 3pi]

It might be easier for you to define y = cos(x), then look at:



You can use the quadratic equation to solve this, discard any solutions that are greater than 1 or less than -1, then take the inverse cosine.

The problem is that this quadratic has no real solutions. Thus you have no real solutions for x. Is there a typo perhaps?

-Dan

I screwed UP!
it should be


3cos(x) + 3 = 2 - 2cos^2(x), for x E [-pi, 3pi]


help is apreciated!

Use the same substitution. You'll get a quadratic.