____
____ -\/ 10
(-\/ 10, --------)
20 ____
____ \/ 10
(\/ 10, ------)
20 [-sqrt(10), sqrt(10)]
(-oo, -sqrt(10)] U [sqrt(10), oo)
[-sqrt(30), 0] U [sqrt(30), oo)
(-oo, -sqrt(30)] U [0, sqrt(30)]