Simple math question..

[dawks]

If you have a base, say x, and the answer of x raised to a power of y is z.. (you know x and z) how do you find the power?

x^y=z

ie 5^y=25 y=?



Also, can one take a number value, and turn it into a fraction... Like how can I convert 1.5 to its fraction form of 3/2..

 

[wfbberzerker]

you can use logs to find it.
for your example:
5^y = 25
y*log(5) = log(25)
y = log(25)/log(5)

 

[marcello]

Originally posted by: dawks
If you have a base, say x, and the answer of x raised to a power of y is z.. (you know x and z) how do you find the power?

x^y=z

ie 5^y=25 y=?



Also, can one take a number value, and turn it into a fraction... Like how can I convert 1.5 to its fraction form of 3/2..

For the first part raise each side of the equation to the power of 1/y.

For the second part, multiply it by whatever is neccesary to make it a whole number, in your example 2. Then take the number you get, and put it over the number you multiplied by, in your example 3/2.

 

[Atomicus]

you take the natural log of both sides


y*ln(5)=ln25

y = ln25/ln5 = 2

 

[BigJ]

One way to do it is doing logs.

y(log(5)) = log(25)

y = (log(25))/(log(5))

y = 2

 

[BornStar]

Well, I would use a log for the first part so you would have y*log(x)=log(z)

I'm not really sure what you're asking in the second part. Are you using a program or something?

 

[ABitTooSpicy]

if x^y = z
then log x (z) = y ------ Log Base x of z = y

EDIT::::

Damn I'm slow =P


2nd EDIT:::

After further thought, for the 2nd part... if you are programming it... you could create a fraction out of the decimal like 1.5 = 1.5/1
Then you could take the number of decimals in the number and multiply top and bottom with that power of 10, so in this case =
(1.5 * 10^1) / (1*10^1) = 15/10 and then do some reducing or something using the GCF...

 

[dawks]

Originally posted by: BornStar18
Well, I would use a log for the first part so you would have y*log(x)=log(z)

I'm not really sure what you're asking in the second part. Are you using a program or something?

marcello answered it I think. but the point was, while using a calculator, it returns values in decimal format. but the teacher prefers fraction format. I was just wanting to convert my decimal result to a fraction.


thanks guys!

 

[Phoenix86]

When converting, remember .999~=1

 

[BigJ]

Originally posted by: Phoenix86
When converting, remember .999~=1

NOOOOOOOOOOOOOOOO!!!!!!!!

::falls over and dies::

 

[Atomicus]

Originally posted by: Phoenix86
When converting, remember .999~=1

let's not start this debate again

 

[Howard]

Originally posted by: Atomicus

Originally posted by: Phoenix86
When converting, remember .999~=1

let's not start this debate again

But it's true.

.999 ~= 1, but .9... = 1.

 

[jman19]

quote:

--------------------------------------------------------------------------------
Originally posted by: Atomicus

quote:

--------------------------------------------------------------------------------
Originally posted by: Phoenix86
When converting, remember .999~=1


--------------------------------------------------------------------------------



let's not start this debate again
--------------------------------------------------------------------------------


But it's true.

.999 ~= 1, but .9... = 1.

:thumbsup:

 

[purbeast0]

OP are you in like 8th grade or something?

 

[jman19]

Originally posted by: purbeast0
OP are you in like 8th grade or something?

We can only hope so.

 

[Gibson486]

Originally posted by: jman19

Originally posted by: purbeast0
OP are you in like 8th grade or something?

We can only hope so.

yes, everyone in this world has great mathmatical ability.....:roll:

 

[Howard]

Originally posted by: Gibson486

Originally posted by: jman19

Originally posted by: purbeast0
OP are you in like 8th grade or something?

We can only hope so.

yes, everyone in this world has great mathmatical ability.....:roll:

You don't need to be a mathematical genius to understand this stuff. I learned it in high school.

 

[xSauronx]

Originally posted by: Howard

Originally posted by: Gibson486

Originally posted by: jman19

Originally posted by: purbeast0
OP are you in like 8th grade or something?

We can only hope so.

yes, everyone in this world has great mathmatical ability.....:roll:

You don't need to be a mathematical genius to understand this stuff. I learned it in high school.

i didnt
my highschool sucked nuts, terrible teachers....awful place. one of my algebra teachers was absolutely nuts; hed work on problems on the board for 20 minutes or so, without talking or explaining anything...and then work on another problem.

ive got a couple math books that ive bought to help me, but overall i find it terribly uninteresting; so I cant pay attention to any of it long enough to learn much; and since i dont require any math thats beyond the very basic, the parts i have learned i dont remember very well if at all :/

that and im lazy