Pre Calculus Repost Please Help

posted by Anonymous

Can someone help me solve this problem:

cos^2x + 5cosx - 2= 0

I am having some trouble finding x

  1. Reiny

    treat it as a quadratic equation where
    cosx = (-5 ± √(25 - 4(1)(-2))/2
    = .37228 or -5.37..
    The second answer lies beyond the range of the cosine function so
    cosx = .37228 and x must be in the first or fourth quadrant.
    x = 68.14 degrees or 291.86 degrees.

    in radians it would be x = 1.18933 or 5.09385

Respond to this Question

First Name

Your Answer

Similar Questions

  1. Trig

    Compute inverse functions to four significant digits. cos^2x=3-5cosx rewrite it as.. cos^2x + 5cosx -3=0 now you have a quadratic, solve for cos x using the equation cosx=(-5 -+ sqrt (25 +12)/2
  2. calculus

    I am working on this problem and having some trouble. We're supposed to use partial fractions. The problem is: integral of dx / (x^6-1) . I got the values of A and D, but I am having trouble with the others. Help please!
  3. math

    Can someone help me solve this problem: cos^2x + 5cosx - 2= 0 I don't know how to find x
  4. Pre Calculus

    Can someone help me solve this problem: cos^2x + 5cosx - 2= 0 I am having trouble finding x
  5. Pre-Calculus

    I'm having trouble with this problem because I'm not sure what to do with the 1.. 21. (x-5)^2+(y+2)^2=1 (x-(5))^2+(y+2)^2= ?
  6. Algebra 1

    I'm having trouble solving x=2(x-1)+6 I understand but I get confused on some of the problem and this is one of them. It's probably very simple to get the answer but can someone please just walk me through on trying to solve it?
  7. Math

    Hello I am having trouble with a pre-calculus problem. The problem is ln|Sin2X-CosX-1|=0 if you could help by listing the steps to solve that would be great! Thanks!
  8. Pre-Calculus

    Hi! I'm having trouble with this math question; can someone help?
  9. Pre-Calculus

    Can someone please explain on how to solve this equation so I can do the others that are similar to this one?
  10. Pre Calculus

    Two forces with magnitudes of 150 and 75 pounds act on an object at angles of 30° and 150°, respectively. Find the direction and magnitude of the resultant force. Round to two decimal places in all intermediate steps and in your …

More Similar Questions