Question 767752
{{{matrix(2,1,"",64^(-2/3))}}}

<pre>
It helps if you know things like 4³=64 and &#8731;<span style="text-decoration: overline">64</span> = 4 

Positive fractions can be written as radicals, but
negative exponents can't, so we have to put 1 over
them with a positive exponent.  Then we use the 
"fraction exponential to radical" rule, which is

{{{matrix(2,1,"", A^(B/C))}}}{{{""=""}}}{{{(root(C,A))^B}}}


{{{matrix(2,1,"",64^(-2/3))}}}{{{""=""}}}{{{matrix(2,1,"",1/64^"2/3")}}}{{{""=""}}}

Now we use the "fraction exponent to radical" rule

{{{matrix(2,1,"",1/(root(3,64))^2)}}}{{{""=""}}}

and since we know that &#8731;<span style="text-decoration: overline">64</span> = 4

that becomes

{{{1/(4^2)}}} 

and finally

{{{1/16}}}

Edwin</pre>