# roots

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• April 28th 2009, 07:43 AM
peteryellow
roots
What are the root of $x^4-8x^2-8x-2?$ I want precise not with decimals.
• April 28th 2009, 10:52 PM
NonCommAlg
Quote:

Originally Posted by peteryellow

What are the root of $x^4-8x^2-8x-2?$ I want precise not with decimals.

$x^4-8x^2-8x-2=x^4-2(2x+1)^2=(x^2-2\sqrt{2}x - \sqrt{2})(x^2+2\sqrt{2}x + \sqrt{2}).$
• April 29th 2009, 05:25 AM
HallsofIvy
And you can use the quadratic formula to find zeros of those two quadratic factors.
• April 29th 2009, 05:27 AM
Bwts
You'll be lucky becuase I get:

3.2620
-2.1796
-0.6488
-0.4335

as your roots

:)

Oops I take that back...........(didnt read the already posted replies duhhh)