Question

calc help @vocaloid

Answer 1

7 and 8 plz

Answer 2

for 7 you just need to take the derivative of the perimeter equation wrt t and plug in dp/dt to solve for dr/dt

for 8 solve for c where f'(c) = 0
you will need to take the derivative of the function

Answer 3

@Shadow I got the derivative but what do I do next?

Answer 4

You are given dp/dt and r

Take the derivative, plug in dp/dt and r, solve for dr/dt

Answer 5

perimeter of a circle = 2pi*r
dp/dt = 2pi * dr/dt

Answer 6

for dr/dt do I plug in radius/time?

Answer 7

could you help me get these solved before 2. I have a meeting today

Answer 8

8. I have the derivative 2/(x+1)^2

Answer 9

@v

Answer 10

@Vocaloid

Answer 11

@Ultrilliam

Answer 12

@Angle

Answer 13

which one are we still stuck on?

Answer 14

7 and 8

Answer 15

do you see them? or do I need to repost

Answer 16

I see them
what do you have so far?

for 7, you have the equation for the perimeter of the circle
which is P = 2*pi*r

and vocaloid has pointed out that taking the derivative in terms of time gives
dp/dt = 2pi * dr/dt

Answer 17

I have that part do I plug in or what do I do next

Answer 18

[honestly it's been a while since I have done a related rates problem]
I think you are given that the "rate of change for the perimeter in terms of time" (i.e. dp/dt)
= 3

so you plug in dp/dt = 3 and get dr/dt

Answer 19

okay so .48 makes sense

Answer 20

8?

Answer 21

we start off with finding
f(4) = ?
and
f(5) = ?

Answer 22

I have the derivative 2/(x+1)^2

Answer 23

I would think so yes

Answer 24

ok ok so for this problem we want to find the slope between f(4) and f(5)

then find the point between 4 and 5 that has the same slope


so first step is to find the slope between f(4) and f(5)

Answer 25

once you find that slope, you set the derivative equal to that number and solve for x

so
2/(x+1)^2 = slope
and solve for x

Answer 26

do you thinl I should graph it to find F(4) and 5

Answer 27

I think you can just plug in?

like f(4) = (4-1)/(4+1) = 3/5
f(5) = (5-1)/(5+1) = 4/6 = 2/3

so slope = (y2 - y1) / (x2 - x1) =
\(= \frac{(2/3) - (3/5)}{5-4}\) = ?

Answer 28

got it ty

Answer 29

4.48

Answer 30

perfect :)