(1 point) Suppose that f(x) = In(7+ x2) (A) Use interval notation to indicate where f(x) is concave up. Note: When using interval notation in WeBWork, you use I for co, -I for -co, and U for the union symbol. If there are no values that satisfy the required condition, then enter "{}" without the quotation marks. Concave up: (B) Use interval notation to indicate where f(x) is concave down. Concave down: (C) Find all inflection points of f. If there are no inflection points, enter -1000. If there are more than one, enter them separated by commas. Inflection point(s) at x =