<span>for that, what you need is a calculator... like say a TI(texas instruments) 83 or 83plus or higher, will do regressions, if you have an android device like a phone or tablet, you can also get an app from the play store "Andie's graph", is a TI calculator emulator, it works just like the calculator itself, you'd only need the ROM
</span><span>that said, you can also use some online calculators for that.
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<span>I could give you a direct link to one, but this site has issues with links, if you do a quick search in google for "keisan exponential regression calculator", it should be the first link, is from the Casio site.
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<span>you could do regressions in a spreadsheet as well.... you could check online for an "addin" or "extension", if you use MS Excel, pretty sure there are some addins for regressions.
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if I recall correctly, Excel does regressions natively, but the addins are just frontends, is all, just some added interfacing.
anyhow, if you have an Android device Andie Graph works peachy, I have an 83plus, 84, 86 in it, they all work just like my old TI83plus.
there's also an app in the play store called Graph89, is an emulator for a TI89, the same you need a tiny little file, and texas instruments provides them, have also, works peachy too.
Without any more information we can't find the actual numerical representation of the length and width but we can give an expression that will allow us to find them...
We let the width equal x, so the length is 3x. That would be the dimensions...
length = 3x
width = x
So to find perimeter the expression would be
2(3x) + 2(x) =
6x + 2x =
8x
For the area it would be
a= length × width
a = 3x × x
a = 3x^2