Question 440905
   -2{{{ root(3,16y^4) - root(3,27y^8) + root(3,81) }}}
     *except all of the roots are not squared, they are cubed.*
It's cube root, not cubed root.
---------------
 -2{{{ root(3,8y^3*2y) - root(3,27y^6*y^2) + root(3,27*3) }}}
=  -2{{{ 2y*root(3,2y) - 3y^2*root(3,y^2) + 3root(3,3) }}}
----------
Nothing can be combined.
It's not clear what the leading -2 applies to.