Taking into account the domain of the function together with the sign chart from the previous part, we have that the function is concave up on the intervals ( − ∞ , − 2 2 ) , ( 2 2 , 3 ) , ( 4 , ∞ ) {\displaystyle \color {blue}(-\infty ,-2{\sqrt {2}}),(2{\sqrt {2}},3),(4,\infty )} .
