Answer:
Ava's solution was not correct. 
The correct solution is 1.
Explanation:
The expression Ava was to simplify(as seen in the attachment) is: 


On substitution of the result above into the denominator, we have:

Therefore:
Ava did not take the square of the negative sign. This led her to have a negative result.
- Ava's solution was not correct. 
- The correct solution is 1.