I can never do these questions. Could someone please give me a full solution?

## 2001 Paper Two Question 9

### Dave

Posted 19 May 2005 - 07:43 PM

A = A

if it says the area doubles then you can say that

a

a = 2

as this sticks to rule

then just sub in these values

2 = 1.e

you can also sub in your value for t given in question

2 = e

to find k we need to get it down from the exponent. To do with we need to cancel off the

e. This can be doen by taking the logs of both sides

ln 2 = 1.5k

k = ln 2 / 1.5

k = 0.46

_{o}e^{kt}if it says the area doubles then you can say that

a

_{o}= 1a = 2

as this sticks to rule

then just sub in these values

2 = 1.e

^{kt}you can also sub in your value for t given in question

2 = e

^{1.5k}to find k we need to get it down from the exponent. To do with we need to cancel off the

e. This can be doen by taking the logs of both sides

ln 2 = 1.5k

k = ln 2 / 1.5

k = 0.46

### SomethingTypical

Posted 19 May 2005 - 08:01 PM

Thanks, I think I may be getting the hang of these. Hopefully there'll not be one tomorrow.

### tupacshakur

Posted 19 May 2005 - 08:46 PM

QUOTE(gary @ May 19 2005, 08:32 PM)

There was a question similar to this la year doubt one will be there this year will most likely be a graph which is worse.

just cos something was in it last year doesnt mean it might not come up again.

are u meaning the graphs were u have to find a and b from log equations and the graphs where u have to get it into the special forumula and say what k and n is?

### tupacshakur

Posted 19 May 2005 - 08:55 PM

you wont think the same type of "collinear" question would of come up in 2003 AND 2004 but it did so these things happen.

### SomethingTypical

Posted 19 May 2005 - 08:58 PM

The only reason I assumed that it wouldn't come up because it came up in 2001 and then in 2004. I know how to do it now but I still would rather that it didn't turn up again.