Answer:

Step-by-step explanation:
Given

Required
Fill the array using doubling and halving
Question is incomplete, as the array is not given.
However, the solution is as follows:

Double 25 and half 68

Double 50 and half 34

The above is now easy to solve

That is the multipliative identity property.
We take the numbers, add them together, then divide by the how many numbers there are:
(34 + 68) / 2
(102) / 2
51
If the discriminant(b^2-4ac) is rational, then the quadratic is rational.
~ThePirc