Question 898711
{{{21n^2-28n-28=0}}} ... The whole equation can be simplified by dividing 7.
{{{3n^2-4n-4=0}}} ... This quadratic equation can be solved by using 3 methods, which are Factorization, Quadratic formula or Completing the Square.

Factorization method is being used here.
{{{(3n+2)(n-2)=0}}}
{{{n=-2/3}}} or {{{2}}}