MATH 1080 Lecture Notes - Lecture 17: Inflection Point, Cubic Function, Inflection
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Page 225 (what you will need for the final exam: for the function of f(x) = 2x3 2x3 12x. Find critical points but need to find the critical numbers first. F" (x) = 6x2 - 6x 12 = 0. = 6(x2 x 2) = 0. = 6(x-2) (x+1) = 2,1 f(2) = 16-12-24 2, 20** f(-1) = -2 3 12 -1, 17** F"" (x) = 0 2x = 6 x = (this is a possible inflection point) Forever concave down all the way to the left. There are no wobbles in the graph due to concavity. When we did the first derivative we didn"t know whether it did a large concavity or not. This is what we are going to study next. Ex2: f (x) 3x4 -4x3 (find all critical points and local extrema) F(x) = x3 (3x 4) x = 0 and x = 4/3 (those are your intercepts) (0,0) (4/3, 0)