Silly math Q

March 31, 2010 3:55 PM

Dumb math question: is there any useful relationship between numbers a, b, and the function a*(a/b)?
posted by xmutex to Science & Nature (10 answers total)

Not sure about formal relationships; I *can* tell you that your function's equivalent to (a^2)/b, if that helps.
posted by Tomorrowful at 4:03 PM on March 31, 2010

What do you mean by relationship? Are you asking how the function changes as a or b increases or decreases?
posted by kingjoeshmoe at 4:06 PM on March 31, 2010

Response by poster: kingjoeshmoe: would there be some tool that could graph the function with the changes in the values of A and B? That would be useful.
posted by xmutex at 4:08 PM on March 31, 2010

If you have a Mac, run Grapher.

Choose 3D Graph.

Type z=y*y/x

See if that helps you in any way.
posted by vacapinta at 4:10 PM on March 31, 2010 [1 favorite]

Could get you started.
posted by Mapes at 4:10 PM on March 31, 2010 [2 favorites]

Maybe if you explained what's going on here we could help a bit more. Are either a or b constants? Both variables?
posted by rancidchickn at 4:13 PM on March 31, 2010

Wolfram Alpha will do this.
posted by martinX's bellbottoms at 4:14 PM on March 31, 2010

Are you asking how changes in a or b affect the function a^2/b? That's just simple differential calculus.

f(a,b) = (a^2)/b
df/da = 2a/b
df/db = -(a^2)/(b^2) ... I think. Damn I'm rusty.
posted by chairface at 4:19 PM on March 31, 2010

chairface: Wolfram will do that for you too.
posted by vacapinta at 4:31 PM on March 31, 2010

For what it's worth, if you define C = A²/B, then A is the geometric mean of B and C.
posted by Johnny Assay at 5:12 PM on March 31, 2010 [2 favorites]