# Rational Zero's problem

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• March 19th 2006, 08:14 PM
kharris82
Rational Zero's problem
Find only the rational zeros. x^4 + 9

Thanks!
• March 19th 2006, 11:44 PM
CaptainBlack
Quote:

Originally Posted by kharris82
Find only the rational zeros. x^4 + 9

Your problem asks for the rational roots of:

$
x^4+9=0
$

This may be rewritten as:

$
x^4=-9
$
.

Now as $x$ is real $x^4$ is positive which contradicts
the equation, so there can be no real roots of $x^4+9=0$, and
so there are no rational roots.

RonL