Once again, Greta is in a pickle! She is trying to solve the following equation and knows she can use $u$-substitution to do it:

$3\operatorname{tan}^2 x −\operatorname{tan} x − 10 = 0$

1. Greta thinks if she lets $u =\operatorname{tan} x$ she can write the problem as a quadratic equation. Show Greta she is correct.

   Hint (a):

   $3u^2 − u − 10 = 0$
   Solve for $u$.
   Then solve for $x$.

2. Use your answer to part (a) to find the value(s) of $x$.

   Partial Answer (b):

   $x =\operatorname{tan}^{−1}(2) ≈ 1.107 + πn$