Derivatives
MORE CRITICAL NUMBERS!!!
Higher-Order Derivatives
Critical Numbers 1
Critical Numbers 2
100

Find the derivative: f(x) = 4x5 -3x2 +7 

20x4 - 6x

100

Find the critical numbers:

f(x) = x2 + 6x

x = -3

100

What is f′′(x) called?

The second derivative

100

Find the critical numbers:

f(x) = x2 - 6x + 5

x = 3

100

What equation do you usually solve to find critical numbers?

f'(x) = 0

200

Find the derivative: f(x) = 6x3 - 8x + 2

18x2 - 8

200
Find the critical numbers:

f(x) = x2 - 10x + 3

x = 5

200

Find f′′(x):

f(x)=3x4−5x2+7x

f′′(x)=36x2−10

200

Find the critical numbers:

f(x) = x2 + 8x + 12

x = -4

200

Find the critical number(s). 

f(x)=x2+2x

x = -1

300

Find the derivative: f(x) = 5x3 - 2x2 + 8x - 1

15x2 - 4x + 8

300

Find the critical numbers:

f(x) = x3 - 12x

x = -2, 2

300

 Find f′′(x):

f(x)=5x3−2x3+8x−1

f''(x)= 30x - 4

300

A student finds f′(x)=2x−8 and says the critical number is x=8. Are they correct and if not what is the correct answer?

No, the student is incorrect. x=4

300

Find the critical number(s). 

f(x) = x3−3x

x = -1, 1

400

Find the derivative: f(x) = 7x4 - 3x3 + 5x2 - 9

28x3 - 9x2 + 10x

400

Find the critical numbers:

f(x) = 3x2 + 12x

x = -2

400

Find f′′′(x):

f(x)=2x5 − 4x3 + x

f′′′(x)=120x2 − 24

400

A student finds f′(x)=3x2 and says there are two critical numbers, x=0 and x = -0. What is wrong?

0 and −0 are the same number, so there is only one critical number.

400
Find the critical numbers:

f(x) = x2 - 4x

x = 2

500

Find the derivative: f(x) = 3x5 - 4x4 + 7x2 - 6x + 10

15x4 - 16x3 + 14x - 6

500

Find the critical numbers:

f(x) = 2x2 - 8x

x = 2

500

f(x)=x6−3x4+2x2 , Find f'''(x)



f′′′(x)=120x3−72x

500

What is the first step in finding critical numbers?

Find the derivative

500

Find the critical numbers:

f(x) = x2

x= 0