Question

CALCULUS HELP>> PLEASE!
find the critical points for
f(x)=x^4-10x^2-6
calculated f'=4x^3-20x
factored out 4x to get f'=4x(x^2-5)
set x^2-5=0 and got sqrt5 as my answer but its not accepted

Answer 1

should be 3 critical points
\[0,\sqrt{5},-\sqrt{5}\]

Answer 2

(A) Interval = [-3,-1].
Absolute maximum =

Absolute minimum =

(B) Interval = [-4,1].
Absolute maximum =

Absolute minimum =

(C) Interval = [-3,4].
Absolute maximum =

Absolute minimum =

here is the second part....i found -sqrt5 to be the max(i think) for part A but i guess it is wrong

Answer 3

Oh OK, now you mention the intervals!

Answer 4

hehe yes, wanted to make sure i had the basics down

Answer 5

The critical numbers are: -√5, 0, and √5

(A) [-3, -1]

Which of the three critical numbers fall in this interval?

Answer 6

-sqrt(5) aaand it doesnt accept it

Answer 7

Right because that is not automatically the answer.

find f(-3), f(-√5), and f(-1). The largest of these values will be the absolute maximum, and the smallest of these values will be the absolute minimum. Go ahead!

Answer 8

yes f(-3) and f(-1) are both -15, f(-sqrt5) is -31 so i guess it would be the min but nonetheless it does not accept......im supposed to plug them into the original equation, correct?

Answer 9

f(-3) = f(-1) = -15 are the absolute maximum and f(-√5) = -31 is the absolute minimum in the interval [-3, -1]

Answer 10

oooookay it wanted the values, not the inputs......thanks man !

Answer 11

Yes! A value is the y value. Get it?

Answer 12

Now do the rest the same way.

Answer 13

haha yes, crystal, just didnt read close enough i guess

Answer 14

Excellent! Need anything else?

Answer 15

yes sir, have to do the same business on the function 3x-11ln(8x)
calculated the derivative to be 3- 11/x
but i dont think that is the correct derivative....

Answer 16

\[\frac{ d(\ln f(x)) }{ dx }=\frac{ f \prime(x) }{ f(x) }\]

If\[y =3x -11\ln (8x)\]then\[\frac{ dy }{ dx }=3-\frac{ 88 }{ 8x }\]Thus\[\frac{ dy }{ dx }=3-\frac{ 11 }{ x } \]Therefore @gnarballs you were correct!

Answer 17

I have to sign out now but i hope that helps!

Answer 18

setting that =0 would the answer be 3/11?
im horrible with fractions

Answer 19

No, it's x = 11/3

Answer 20

OK? Is that good because I have to go.

Answer 21

yes its awesome.....thanks man.....have a good thanksgiving

Answer 22

I'm from Canada, where we have thanksgiving in October. LOL But thanks and you have yourself a great one also!

Answer 23

ooohh wuuut aha welp have a good day tomorrow then, thanks again

Answer 24

Thanks, bye!