Question

which points are the best approximations of the relative maximum and minimum of the function f(x)=x^3+3x^2-9x-8

Answer 1

theser are the answer options HELP!!

Answer 2

find f'
find roots of f'=0
check them by f' sign table or ,sign of f'' to find out max or min

Answer 3

find f'(x) and then equate to 0 to find the critical points

Answer 4

then check f"(x) at each point.

Answer 5

would it be B??

Answer 6

i really need please pls someone

Answer 7

we have not solved yet. you solve t and show ,we will guide you.

Answer 8

i just dont even know where to start..

Answer 9

differentiate with respect to x

Answer 10

\[f \prime \left( x \right)=3x^2+6x+9\]equate it to zero and find values of x

Answer 11

correction
it is -9 not +9

Answer 12

so f(x) = 9 when equated to 0??

Answer 13

no
\[f \prime \left( x \right)=0~means~3x^2+6x-9=0\]
divide by 3

Answer 14

oh
so
x^2 + 2x - 3 = 0

Answer 15

make factors

Answer 16

x^2+(3-1)x-3=0
x^2+3x-1x-3=0

Answer 17

how do u make factors

Answer 18

3-1=-3
3*-1=-3

Answer 19

correction 3-1=2

Answer 20

coefficient of x^2*constant term is same as the product of two terms (made from coefficient of x)

Answer 21

ok i still dont understand ugh

Answer 22

coefficient of x^2=1
constant term=-3
product=1*-=-3
if the product is negative always subtract something to make the middle term
here 2=3-1
product of 3*-1=-3

Answer 23

i am leaving for sometime . i will be back to help you after 5 minutes.

Answer 24

ok

Answer 25

nevermind i figured it out

Answer 26

i am here.

Answer 27

have you found f"(x)

Answer 28

Have you calculated critical points?
\[f \prime \prime \left( x \right)=6x+6\]

Answer 29

x(x+3)-1(x+3)=0
(x+3)(x-1)=0
x+3=0,x=-3
or x-1=0,x=1

Answer 30

\[f \prime \prime \left( -3 \right)=?\]