Let . Find the open intervals on which is concave up (down). Then determine the -coordinates of all inflection points of .
Notes:
In the first two, your answer should either be a single
interval, such as (0,1), a comma separated list of intervals, such as (-inf, 2), (3,4), or the word
"none".
In the last one, your answer should be a comma separated list of values or the word
"none".
You can earn partial credit on this problem.