How do you calculate 3 = 1.09^x

[E equals MC2]

I know the answer is 12.75, but how do I 'undo' the power when itself is not defined (x) therefore I can't simply root it to the other side?

What's the simplest way?

 

[XZeroII]

you ask a bunch of people on an internet forum.

 

[Rufus12]

Logarithm?

 

[Epic Fail]

divide by 42

 

[PottedMeat]

ln (3) = x ln ( 1.09 )

ln 3 / ln 1.09 = x

 

[Special K]

3 = 1.09^x

take the log on both sides:

log base 1.09(3) = x

now use the change of base formula:

log10(3)/log10(1.09) = x

x = 12.7483

 

[nismotigerwvu]

i can do it on paper but it isn't so clear in a post...also its approximately 12.75 not exact you know....play with the natural log a bit and it'll make sense

 

[OdiN]

Originally posted by: Epic Fail
divide by 42

You are certainly living up to your name.

 

[E equals MC2]

Originally posted by: Special K
3 = 1.09^x

take the log on both sides:

log base 1.09(3) = x

now use the change of base formula:

log10(3)/log10(1.09) = x

x = 12.7483

:beer: thanks.

 

[Stuxnet]

ln of both sides

 

[hiromizu]

Almost 30 and I've forgot how to do basic addition and subtraction. I can't even do something simple like 3433+3999 without spending some time on it. It's scary.

 

[Aharami]

man I need to relearn high school math. This is sad

 

[nakedfrog]

Originally posted by: OdiN

Originally posted by: Epic Fail
divide by 42

You are certainly living up to your name.

Everybody knows 6 x 9 = 42

 

[nonameo]

Originally posted by: nakedfrog

Originally posted by: OdiN

Originally posted by: Epic Fail
divide by 42

You are certainly living up to your name.

Everybody knows 6 x 9 = 42

So what's you + me + 67?

 

[clamum]

Originally posted by: hiromizu
Almost 30 and I've forgot how to do basic addition and subtraction. I can't even do something simple like 3433+3999 without spending some time on it. It's scary.

C'mon man. Add 4000 to 3433, you can do that in your head, then subtract one.

 

[OdiN]

Originally posted by: clamum

Originally posted by: hiromizu
Almost 30 and I've forgot how to do basic addition and subtraction. I can't even do something simple like 3433+3999 without spending some time on it. It's scary.

C'mon man. Add 4000 to 3433, you can do that in your head, then subtract one.

lol yeah I was gonna say.

 

[Born2bwire]

Originally posted by: OdiN

Originally posted by: Epic Fail
divide by 42

You are certainly living up to your name.

Damn straight, the answer is always pi/2.

 

[hdeck]

i minored in math and couldn't remember to do ln off the top of my head *sigh*

 

[A5]

The people saying to use ln() should remember that he isn't dealing with e

 

[Taejin]

Originally posted by: A5
The people saying to use ln() should remember that he isn't dealing with e

uhh..it doesn't matter?

 

[Cattlegod]

excel solver.

 

[Special K]

Originally posted by: A5
The people saying to use ln() should remember that he isn't dealing with e

It doesn't matter. See PottedMeat's solution above. The steps to get the final answer are slightly different if you use ln, but it still works.

 

[z0mb13]

Originally posted by: Taejin

Originally posted by: A5
The people saying to use ln() should remember that he isn't dealing with e

uhh..it doesn't matter?

BOOOOOOMMM HEADSHOT!!!

 

[jman19]

Originally posted by: OdiN

Originally posted by: Epic Fail
divide by 42

You are certainly living up to your name.

Yeah.

You obviously multiply by 42 in this situation.

 

[jman19]

Originally posted by: Taejin

Originally posted by: A5
The people saying to use ln() should remember that he isn't dealing with e

uhh..it doesn't matter?

:thumbsup: