# roots

• Apr 28th 2009, 08:43 AM
peteryellow
roots
What are the root of $x^4-8x^2-8x-2?$ I want precise not with decimals.
• Apr 28th 2009, 11:52 PM
NonCommAlg
Quote:

Originally Posted by peteryellow

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

$x^4-8x^2-8x-2=x^4-2(2x+1)^2=(x^2-2\sqrt{2}x - \sqrt{2})(x^2+2\sqrt{2}x + \sqrt{2}).$
• Apr 29th 2009, 06:25 AM
HallsofIvy
And you can use the quadratic formula to find zeros of those two quadratic factors.
• Apr 29th 2009, 06:27 AM
Bwts
You'll be lucky becuase I get:

3.2620
-2.1796
-0.6488
-0.4335