Help! Keep getting inflection points wrong

Results for this submission Entered Answer Preview Result Message (-1, 0) (-1, 0) correct (-infinity,-1), (0, infinity) (-00, -1), (0, 00) correct Your first value isn't a number (it looks like a list of numbers) (-1, 0), (0, -3), (0, 2) (-1,0), (0, -3), (0, 2) incorrect Your second value isn't a number (it looks like a list of numbers) Your third value isn't a number (it looks like a list of numbers) At least one of the answers above is NOT correct. (1 point) Let f(x) = -x* - 2x' + 6x + 2. Find the open intervals on which f is concave up (down). Then determine the x-coordinates of all inflection points off. 1. f is concave up on the intervals (-1,0) 2. f is concave down on the intervals (-inf,-1),(0,inf) 3. The inflection points occur at x = (-1,0),(0,-3),(0,2) 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&quot