Question 6 of 12. Step 1 of 1 Correct Use the Second Derivative Test to find all local extrema, if the test applies. Otherwise, use the First Derivative Test f (x) = x4 - 20x3 - 8 Answer Keypad Keyboard Shortcuts Enter any local extrema as an ordered pair, and separate multiple answers with commas. Selecting a radio button will replace the entered answer value(s) with the radio button value. If the radio button is not selected, the entered answer is used. Local Maxima: No Local Maxima Local Minima: O No Local Minima