title: using lm(poly) to get formula coeff
body: <p>I'm trying to using lm(poly) to get a polynomial regression for some points, but got some questions about the regression formula coefficients it returns.</p>
  
  <p>sample like this:</p>
  
  <pre>
  x=seq(1,100)
  y=x^2+3*x+7
  fit=lm(y~poly(x,2))
  </pre>
  
  <p>Results are:</p>
  
  <p><code>lm(formula = y ~ poly(x, 2))</code></p>
  
  <p>Coefficients:</p>
  
  <pre>
  (Intercept)  poly(x, 2)1  poly(x, 2)2  
         3542        30021         7452  
  </pre>
  
  <p>Why are the coefficients not 7,3,2?</p>
  
  <p>Thank you very much!</p>