Question 111065
{{{4 ^ -2 -  4 ^ -1 }}}

= {{{1/4^2}}} – {{{1/4^1}}}

= {{{1/8}}} -{{{1/4}}}……….multiply {{{1/4}}} by {{{2}}} to get denominator  {{{8}}} 
and it will be: {{{1/4 = 2/8}}} 

=  {{{1/8}}}–{{{2/8}}}

=  {{{-1/8 }}}