The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

A level maths help required

The latest question will be on the last page


area of circle increases at uniform rate of 8cm^2min^-1 calculate rate radius increases when circumference is 50cm

i think i need to calculate dr/dt da/dt = 8 but how do i do the rest?

LASTES QUESTIONS ON LAST PAGE. :smile:
(edited 10 years ago)

Scroll to see replies

Reply 1
Avatar for TenOfThem
TenOfThem
18
So

I am assuming that a circle is involved
Reply 2
Avatar for SexyNerd
SexyNerd
OP
17
Original post by TenOfThem
So

I am assuming that a circle is involved


:biggrin:
Reply 3
Avatar for TenOfThem
TenOfThem
18
Original post by SexyNerd
:biggrin:


Ok

so you know a formula connecting a and r that you could use to find da/dr
Reply 4
Avatar for SexyNerd
SexyNerd
OP
17
its a private affair. :tongue:
Reply 5
Avatar for SexyNerd
SexyNerd
OP
17
Original post by TenOfThem
Ok

so you know a formula connecting a and r that you could use to find da/dr


???

got it
(edited 11 years ago)
Reply 6
Avatar for SexyNerd
SexyNerd
OP
17
blatantly jell
Reply 7
Avatar for SexyNerd
SexyNerd
OP
17
i got it, how do i get the g(x) of a function?
Reply 8
Avatar for TenOfThem
TenOfThem
18
Original post by SexyNerd
i got it, how do i get the g(x) of a function?


could you try to give a whole question
Reply 9
Avatar for SexyNerd
SexyNerd
OP
17
Original post by TenOfThem
could you try to give a whole question


:colondollar:

g(x) =x(x+1)(x+2)

sketch g(x) and g^-1 on same axes
Original post by SexyNerd
i got it, how do i get the g(x) of a function?



Original post by SexyNerd
:colondollar:

g(x) =x(x+1)(x+2)

sketch g(x) and g^-1 on same axes


Ok that is just a cubic graph ... so you can draw that I hope

As for the inverse function ... bit tougher with a cubic
Reply 11
Avatar for SexyNerd
SexyNerd
OP
17
Original post by TenOfThem
Ok that is just a cubic graph ... so you can draw that I hope

As for the inverse function ... bit tougher with a cubic


yes, i drew the first, how would i draw the g^-1
Original post by SexyNerd
yes, i drew the first, how would i draw the g^-1


Use the line y=x

Reply 13
Avatar for SexyNerd
SexyNerd
OP
17
Original post by steve2005
Use the line y=x



i got g(x) crossing at 0, -1, -2

how do i calculate g((x)^-1
Original post by SexyNerd
i got g(x) crossing at 0, -1, -2

how do i calculate g((x)^-1



This is an example, it is not your graph.
Reply 15
Avatar for Dan12
Dan12
Original post by SexyNerd
area of circle increases at uniform rate of 8cm^2min^-1 calculate rate radius increases when circumference is 50cm

i think i need to calculate dr/dt da/dt = 8 but how do i do the rest?


ok think about the equation you use when finding area of circle (i.e. A=pi r^2)
dr/dt = da/dt x dr/da

hope that helps
Reply 16
Avatar for SexyNerd
SexyNerd
OP
17
Oh,
Original post by steve2005
This is an example, it is not your graph.


oh, how would i get g(x)^-1
Original post by SexyNerd
Oh,

oh, how would i get g(x)^-1


g(x) and g^(-1)(x) are symmetrical about the line y = x. Once you have one graph it is easy to draw it's reflection.
Reply 18
Avatar for SexyNerd
SexyNerd
OP
17
Original post by TenOfThem
could you try to give a whole question


(((x+1)^5)^1/2) / x how would you differentiate this?
Original post by SexyNerd
(((x+1)^5)^1/2) / x how would you differentiate this?


Using the quotient and chain rules

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you