[R] Non-linear "linear" models?

[eph1v3t8-rhls6783@mailblocks.com]

Hi,
    I'm new to R (though I have spent hours trying to learn how to use 
it) and also not very knowledgeable
about statistics, so I hope you will excuse what may seem like a very 
basic question. I'm trying to use
R to do an ANOVA analysis for some data with an unbalanced design, and 
while I was trying to figure that out, I got confused about the purpose 
of the "lm". All definitions I can find of "linear model" are of the 
form:
y = a + b * x + e

  In other words, y is only linear in the dependent variable(s) x. 
However, the lm model seems to support higher order polynomials, e.g.:

> lm(dist ~ speed + I(speed^2)+I(speed^3), cars)

  Is there some sense in which that model is "linear", or is R's lm() 
providing extra functionality?

Thanks,
--Paul


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