Points of Inflection and Intervals of Concavity

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Points of Inflection and Intervals of Concavity

The position of a particle moving along an axis is modeled by s(t) = t

3

-2t

 Find any times when the velocity of the particle is constant.

 Find any intervals where the velocity is increasing.

 Find any intervals where the velocity is decreasing.

 Find the intervals where the particle is speeding up

s(t) = t 3 -2t

Graph the position function

Mark the points on the position function when the velocity is constant.

Locate the intervals when the velocity is increasing on the graph of the position function.

Locate the intervals when the velocity is decreasing on the graph of the position function.

How does the graph of the position function differ when the velocity is increasing rather than decreasing?

Vocabulary

Know:

Critical pointspossible extrema, where first derivative =

0 or derivative doesn’t exist, but original function does exist

Now:

Relative extremacritical points where change in sign in first derivative before or after

Intervals of Increaseintervals where first derivative is positive

Intervals of Decreaseintervals where first derivative is negative

Possible inflection pointswhere second derivative = 0 or doesn’t exist, but original function does exist

Inflection pointspossible inflection points where there is a change in sign in the second derivative before or after

Concave upintervals where second derivative is positive

Concave downintervals where second derivative is negative

For f(x) = 5x 3 -5x+6

 Find intervals of increase, decrease, relative extrema (label as max. or min.)

 Find inflection points, intervals of increase or decrease.

2 x

2 

4 x

f(x) =

 Find intervals of increase, decrease, relative extrema (label as max. or min.)

 Find inflection points, intervals of increase or decrease.

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