-√23 rational or irrational ? Irrational
17/18 rational or irrational ? Rational
-√81 rational or irrational ? Rational
For this case, we must represent the numbers that are included between -4 and 6. Let "x" be the variable that represents these numbers, then we have:

If the set includes -4 and 6 then we have:

Answer:
or

Answer:
x=6
Step-by-step explanation:
Given the x-intercepts of a parabola: 
The equation of symmetry at the parabola's vertex is x=h
Where 
In this case,

Therefore, the line of symmetry of the parabola is x=6 and is also the x-coordinate of the parabola's vertex.
Step-by-step explanation:
i hope this helps