This discussion is now closed.

Check out other Related discussions

I need help solving this.

2^n + 3n = 0

The solution is between 0 and -1. Does that help?

Edit: Oops!

OP

No.

Do you understand iteration?
Can you make n the subject?
One simple rearrangement will work, the other won't.

Reply 4

Rubgish

13

Is this degree level? Because if it isn't, you'll just have to use approximation methods. If its degree level its still not a pretty answer, use the lambert w-function on it.

If you want an answer without using a numerical method, the Lambert W function is going to put in an appearance again.

Reply 6

Crazy Paving

OP

17

Yeah I think it's third year degree level maths.

You think it is? Don't you know?

Google the Lambert W function and you will see what to do.

Reply 8

Nautivela

log(2)-3n=n

(1/n)log(2)-3n=1

log(2)(-3n)^1/n=1

(-3n)^1/n=2

1/(-3n)^n=2

(-3n)^n=1/2 - Plot this on a graph y= (-3n)^n
y= 1/2
The answer is the x value of the intersection

Sorry for the notation :frown:

log(2) means 2 is the base

Reply 9

Crazy Paving

OP

17

Long story. I am a first year Economics student and I know a third year Economics student who is friends with a third year Maths student and we have a bet to see who can solve it first. :yep:

So just giving me the answer will suffice.

Reply 10

Crazy Paving

OP

17

Mr M you changed your post. I didn't understand why it would be between 0 and 1. Between 0 and -1 does help a bit more though.

Not enough, however.

Crazy Paving

So just giving me the answer will suffice.

Not a chance. You can expect thirty different wrong answers now.

Crazy Paving

Mr M you changed your post. I didn't understand why it would be between 0 and 1. Between 0 and -1 does help a bit more though.

Not enough, however.

Yes I made a typo. The answer is between 0 and -0.5 if that makes you any happier.

Reply 13

Crazy Paving

OP

17

How would I go about solving it though? I've tried rearranging, using logs etc and am getting nowhere. :frown:

Crazy Paving

How would I go about solving it though? I've tried rearranging, using logs etc and am getting nowhere. :frown:

Will an approximate answer do? Make 3n the subject and then divide by 3. There is your iterative formula.

Reply 15

Crazy Paving

OP

17

So it's just a case of trial and error then?

Reply 16

little_wizard123

19

Crazy Paving

So it's just a case of trial and error then?

Ignore the log method posted above. He's saying you need to use an iterative method, which will invole getting it into the form n=... . Look up iterative methods.

Indeed wizard. I foolishly assumed a first year Economics undergraduate might have taken A Level mathematics but that looks like that might not be the case.