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 #1
avatar+33665 
+5
Nov 16, 2014
 #9
avatar+118724 
0
Nov 16, 2014
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Nov 16, 2014
 #4
avatar+118724 
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Nov 16, 2014
 #4
avatar+118724 
+8

How much of this do you need to do by hand?

 

Well here is a relevant graph

https://www.desmos.com/calculator/mtrfxxuwrs

 

I can see from the graph that y=x

$${{\mathtt{x}}}^{{\mathtt{6}}}{\mathtt{\,-\,}}{{\mathtt{x}}}^{{\mathtt{4}}} = {\mathtt{18}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{\,-\,}}{\sqrt{{\mathtt{3}}}}\\
{\mathtt{x}} = {\sqrt{{\mathtt{3}}}}\\
{\mathtt{x}} = {\mathtt{\,-\,}}{\sqrt{{\sqrt{{\mathtt{5}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,-\,}}{\mathtt{1}}}}\\
{\mathtt{x}} = {\sqrt{{\sqrt{{\mathtt{5}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,-\,}}{\mathtt{1}}}}\\
{\mathtt{x}} = {\mathtt{\,-\,}}{\sqrt{{\mathtt{\,-\,}}{\sqrt{{\mathtt{5}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,-\,}}{\mathtt{1}}}}\\
{\mathtt{x}} = {\sqrt{{\mathtt{\,-\,}}{\sqrt{{\mathtt{5}}}}{\mathtt{\,\times\,}}{i}{\mathtt{\,-\,}}{\mathtt{1}}}}\\
\end{array} \right\}$$

 

so the real solutions are 

$$(-\sqrt3,-\sqrt3),\quad (\sqrt3,-\sqrt3),\quad (-\sqrt3,\sqrt3),\quad and \quad (\sqrt3,\sqrt3)$$

 

NOW how much of this did you really need to do by hand?   

Nov 16, 2014

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