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Homework Help: Vertical compression question

  1. Feb 7, 2006 #1
    Q. Given f(x)=2(x^2)-4 , determine the new equation g(x) after a vertical compression by a factor of 1/2.

    The answer provided by the book is g(X) = (x^2)-2, but shouldn't it be g(x) = (x^2)-4 ?

    Help will be much appreciated.


  2. jcsd
  3. Feb 7, 2006 #2


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    Science Advisor

    No, the book's solution is correct. Horizontal changes are changes in x, vertical changes are changes in y. Since this is a vertical compression by 1/2, first calculate y= 2x2- 4, the calculate (1/2)y= (1/2)(2x2- 4)= x2- 2 (becareful to use the "distributive law"- multiply both parts by 1/2). The new y is y= x2- 2.
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