View Full Version : log(a+b)
anyoen know how to expand this? i can't think of any obvious way...
What kind of result are you looking for - functions of a and b separately? As it stands, it is as simple as possible.
CRGreathouse
Nov2-05, 04:40 PM
There's not much you can do. In some cases, it's useful to factor it as \log a+\log(b+1), but in general there's nothing simpler than the way you wrote it.
i have a deceptively simple question you see:
X^3 = (cY+d)^2
where c and d are constants, with x and y the variables. how would you plot the 2 variables as a straight line graph. i'm having an idiocy attack and can only think "log it...."
Learning Curve
Nov2-05, 04:44 PM
Take the log of Y and graph x, log y.
that doesn't plot that relationship as a straight line though does it?
i was under impression you had to transform [said equation] into a y=mx+c type form
that doesn't plot that relationship as a straight line though does it?
i was under impression you had to transform [said equation] into a y=mx+c type form
You can't plot things like x^3=y^2 as a straight line on a normal graph.
Learning Curve
Nov3-05, 10:51 AM
I didn't mean that would give you a formula, but if you had a set of data, you could find the regression by plotting x, log y. It's not the answer but it's a way to get it.
that doesn't plot that relationship as a straight line though does it?
i was under impression you had to transform [said equation] into a y=mx+c type form
No, none of log-log, log-linear or linear-log will make that equation a straight line.
What's the full context of the problem, do you have a number (more than 2) of x,y points and you wish to find constants c and d that give the "best fit" in some particular sense?
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