Suppose that
f(x) = \ln(4 + x^2)

(A) Use interval notation to indicate wheref(x) is concave up.

** Note: ** When using interval notation in WeBWorK, you use
** I ** for \infty , ** -I ** for -\infty , and
** U ** for the union symbol. If there are no values that satisfy the
required condition, then enter "{}" without the quotation marks.

(A) Use interval notation to indicate where

Concave up:

(B) Use interval notation to indicate where

Concave down:

(C) Find all inflection points of

Inflection point(s) at

You can earn partial credit on this problem.