Question 117096
<pre><font facr = "book antiqua" size = 5 color = "brown"><b>
numerator 4
denominator -2+sqrt7

{{{4/(-2+sqrt(7))}}}

{{{4/(-2+sqrt(7))}}}×{{{(-2-sqrt(7))/(-2-sqrt(7))}}}

{{{(4(-2-sqrt(7)))/(-2+sqrt(7))(-2-sqrt(7)) }}}

{{{(4(-2-sqrt(7)))/((-2)(-2)+2sqrt(7)-2sqrt(7)-sqrt(7)sqrt(7))   }}}

{{{(4(-2-sqrt(7)))/(4+7)   }}}

{{{(4(-2-sqrt(7)))/11}}}

You can leave it like that, but you can
improve on the way it looks. You can 
multiply the top out:

{{{(-8-4sqrt(7))/11}}}

Then factor out -4 on top

{{{(-4(2+sqrt(7)))/11}}}

Then put the negative sign out in front,

{{{-(4(2+sqrt(7)))/11}}}

The reason to learn to improve on the way
an expression looks is because in multiple
choice tests, sometimes the answer you get
will not be listed as one of the choices
in the form you have it in, for it is in
listed in an "improved" form as above.  If 
you do not learn to improve upon the way 
expressions look, you may miss some problems 
even though you worked them correctly.

Edwin</pre>