What is the range of the function in the graph?
(i've never been good at these, could someone ? )

Locate the highest or lowest point on the graph. In this case, there is no highest point. There is only the lowest point. That lowest point is (2,0). 

The y coordinate of that lowest point is y = 0. This is the smallest y can be. The value of y cannot be any smaller. This forms the left boundary of the interval notation answer.

There is no upper boundary on how high y can go. It can grow forever. Therefore the right boundary of the interval is infinity

This is why the answer is the interval notation answer 
The square bracket indicates "include this value in the set" while a parenthesis says "exclude this value". We can never reach infinity so infinity is always with a parenthesis

Final Choice A

Note: the interval notation answer for choice A is the same as writing  (y is greater than or equal to 0)

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2