1. ## Power Regression

I have a Math Internal Assessment that I'm doing (basically a Math Essay...) and for one of the parts I have to find an equation for the data given. I have tried all the regressions on my calculator and found that Power Regression gives the best equation that fits the graphed data. I have a program on my computer that can do power regression, though I need to know how to do the power regression by hand (I have to "show" how I got that graph).

any input would be appreciated and sorry if this is the wrong forum because I don't really have any idea where it should go.

I know that the formula is ax^b, but I do not know what a nor b stands for...

2. I'm not sure how much by hand you want to do

but you basically are doing a log- log plot

y= a x^b

lny = ln(a) + bln(x)

so graph your points on a ln(y) versus ln(x)

the slope is b and the intercept is ln(a)

3. So basically I start off with the equation y=mx+b and from that I use m=b and b=a?

4. yes but perhaps I chose a confusing choice of variables

Let

y= ax^t

ln(y) = ln(a) + tln(x)

m =t c = ln(a)

and a = e^(c)

5. ## Correction

See edits to previous posts

I wrote y = ab^x instead of ax^b

sorry

At some point you'll need technology

I've included an example where I used Mathcad to do a power regression

6. thanks for all your help. And yes, I know that I do need to use technology at some point to for it, though I need to make sure that they know that I am using some math instead of just using technology for everything.

And thanks for the mathcad .pdf, I have mathcad and I guess I'll install that now and use it (it's way better than excel, except more confusing...)

7. If interseted I've created 2 web sites using Mathcad

Calculus Animations which is a collection of animations and lecture notes

and what may be of more immediate use for learning the basics of mathcad