The answer is not (-1/2, 1/10). Thank you!
The answer is (-1/10, 1/10).
2u u cannot equal or be less than - 1/2 because 2(-1/2) = -1
-20 u u cannot equal or be MORE than 1/20 because -20 ( 1/10) = -1
[-1/2, 1 /20] edited sorry for the math error
If u >= -1/2 then 2u is not in the interval
If u <= 1/20 then -20u is not in the interval
So we must have u in the interval [-1/2, 1/20]
+36915 
