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Homework Help: Find all roots of a function

  1. Mar 13, 2010 #1
    x^4 + 7x^2 + 6 =0

    I know the answers are imaginary but I don't remember how to solve this equation.
     
  2. jcsd
  3. Mar 13, 2010 #2
    Let t=x^2 and solve for t. Then once you have t, you can easily find x.
     
  4. Mar 13, 2010 #3
    If I do that and solve for t, I obtain two real solutions when all 4 all imaginary.
     
  5. Mar 13, 2010 #4
    using quadratic formula:

    [tex] x^2=\frac{-7\pm \sqrt{49-24}}{2}[/tex]
    [tex] x^2=\{-6,-1\} [/tex]

    both values of x^2 for negative, so all 4 values of x are imaginary. Check your working?
     
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