We need to find the values of "a" that result in the function being real. For that the number inside the square roots must be greater or equal to zero, therefore:
[tex]q^2+a\text{ }\ge0[/tex]We need to isolate the "a" variable on the left side now.
[tex]a\text{ }\ge-q^2[/tex]The value of "a" is anything greater or equal to -q².
