Question 599571
Work out the value of 9 to the power of -3/2
the reciprocal will get rid of the negative; exponent 1/2 is the same as square root, so write it 
{{{1/9^(3/2)}}} = {{{1/(sqrt(9^3))}}},
factor inside the radical to reveal a perfect square
{{{1/(sqrt(9^2*9))}}},
extract the perfect square
{{{1/(9*sqrt(9))}}},
we know what the square root of 9 is
{{{1/(9*3)}}} = {{{1/27}}}