Answer:
If a is negative or zero there are no real solutions
Explanation:
y=ax^2-8
Set equal to zero to find the solution
0 =ax^2-8
Add 8 to each side
8 = ax^2
Divide by a a cannot be zero or we cannot divide by it
8/a = x^2
Take the square root of each side
sqrt(8/a) = sqrt(x^2)
We need 8/a to be positive for it to have real solutions
That means a has to be positive
If a is negative or zero there are no real solutions