Suppose $x = e^{2t}$.

1. Find the value of the expression $x''' - 6 x'' + 12 x' - 8 x$ in terms of the variable $t$. (Enter the terms in the order given.)
   + + + help (formulas)
   
   
2. Simplify your answer to the previous part to obtain a differential equation in terms of the dependent variable $x$ satisfied by $x = e^{2t}$.
   $x''' - 6 x'' + 12 x' - 8 x =$ help (formulas)
   
   
3. Is $x = e^t$ a solution to your differential equation in the previous part? Choose Yes No Be sure you can justify your answer.