I think "D", for both cases x = 1
Banerjeea, I would appreciate if you could explain your solution.
Second is certainly a pretty straightforward case. However, in case 1, how can you get (only) x=1 from a third degree equation? I think you should have 3 roots for an equation of the third order (unless you've repeated roots, like in the second case). Because if there're other roots too, then we cannot say for sure the value of the expression, because of multiple values of x giving multiple values of the expression.
Furthermore, in arriving at x=1 as a solution, did you simply start with substitution? How did you solve the equation of the third degree?
Who says elephants can't dance?