Question

Find all critical numbers for the function
f(x)=9x3−27x+4,
and then list them (separated by commas) in the box below. If there are no critical numbers, enter None.

Answer 1

@Chlorophyll can you give me a hand?

Answer 2

Critical numbers is obtained when let y' = 0 and y" = 0

Answer 3

all of them, so all i need to do is find the zeros of the derivative?

Answer 4

so for this question 27 (x^2-1) x=1, and x=-1

Answer 5

so then i plug that into original equation and find y?

Answer 6

so 9(1)^3−27(1)+4=-14
and 9(-1)^3−27(-1)+4=22

Answer 7

so (-1,22) and (1,-14) are critical numbers?

Answer 8

how would i find y"?

Answer 9

so again roots of y; are 1 and -1

Answer 10

and root of y'' =0

Answer 11

idk doesnt sound familiar so im guessing not

Answer 12

so what is my answer?

Answer 13

it says that my answer isnt a number its a list of numbers

Answer 14

so try that as an answer?

Answer 15

because that didnt work either

Answer 16

idk just telling you what i was told

Answer 17

Maybe you should link me to the source page or your post is incorrect!

Answer 18

doubt it will work but here it is
https://webwork.uwstout.edu/webwork2/math-153-003-fa12/Math153_HW26_Maximum_and_Minimum_Problems/4/?user=relichn0145&effectiveUser=relichn0145&key=SIKe6HI22nYBXJd6enAWqHeHVfPURVgs&displayMode=MathJax&showOldAnswers=1

Answer 19

brb got to go eat

Answer 20

This is not the same problem!
( Yes, late dinner time here, too! )

Answer 21

Try x = 3

Answer 22

im sorry must have been scanning the questions try this
https://webwork.uwstout.edu/webwork2/math-153-003-fa12/Math153_HW26_Maximum_and_Minimum_Problems/1/?effectiveUser=relichn0145&displayMode=MathJax&showOldAnswers=1&user=relichn0145&key=QJ0OTtEADUBFSjvnzPRb5WAF80L7Vq0K

Answer 23

i figured it out it was 1,-1

Answer 24

http://openstudy.com/study#/updates/50905f94e4b0ad6205378b1b

Answer 25

Oh, they means critical NUMBERS are just X values, (without y values ), Hmm!

Answer 26

ya i guess so

Answer 27

yup but that first link that i sent you i cant get it for some reason i got 3 as an answer

Answer 28

You had the answer x= 3?

Answer 29

correct

Answer 30

x=-3 sorry

Answer 31

Mine is x = 3

Answer 32

didnt work either

Answer 33

Yes, your x = -3 is correct!

Answer 34

i guess it was none for some reason