Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative...

4
Critical Numbers and Finding Extrema

Transcript of Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative...

Page 1: Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative of f(x) 2.Set the derivative equal to zero 3.Solve.

Critical Numbers and Finding Extrema

Page 2: Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative of f(x) 2.Set the derivative equal to zero 3.Solve.

Critical Numbers

04

1

14

14

140

4)(

4)(

14)(

2

2

2

2

2

1

x

x

x

x

x

xxf

xxxf

xxxf

0

60

6)(

33)( 2

x

x

xxf

xxf

Example 1:

Example 2:1. Take the derivative

of f(x)2. Set the derivative

equal to zero3. Solve for x

*Remember to test the regions to make sure the critical numbers are valid

you can’t take the square root of a negative number, so the only critical number is 0

Page 3: Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative of f(x) 2.Set the derivative equal to zero 3.Solve.

Finding Extrema(closed interval, continuous function)

1. Find critical numbers2. Find endpoint values3. Find the function values for the x values

determined in step one and two4. Identify extrema

a. Largest overall function value is the absolute maxb. Smallest overall function value is the absolute

min

Page 4: Critical Numbers and Finding Extrema. Critical Numbers Example 1: Example 2: 1.Take the derivative of f(x) 2.Set the derivative equal to zero 3.Solve.

Finding Extrema Example

Find the absolute min and max for the function on the interval [-3,5] :

2,2

)2)(2(30

)4(30

123)(

112)(

2

2

3

x

xx

x

xxf

xxxf

66)5(

10)3(

15)2(

17)2(

f

f

f

f

Absolute max is 66 and occurs at x=5 and the absolute min is -15 and occurs at x=2