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Homework Help: Graphing of y² graphs

  1. Nov 7, 2009 #1
    Hi everyone. I am familiar with the graphing of y² graph which is essentially sqrt of the graph then reflected in the x-axis.

    However, I am confused at the points where the y= graph cuts the x-axis. According to differentiation, the gradient of the sqrt y graph should have a sqrt y at the denominator using quotient rule. If y=0, the gradient should be infinity. However, I do see some graphs with some other shapes (some crossing, some flat) at the x-axis so Im wondering about this.

    Hope someone can help to clarify my problems.
  2. jcsd
  3. Nov 7, 2009 #2


    User Avatar

    Have you tried simply plugging in points and making a rough graph?
  4. Nov 7, 2009 #3
    Yeah of course that would work but I was wondering if there is a general rule to see aside from just plotting it out since some question dont give the equation but just give a pictorial graph and ask you to transform.
  5. Nov 8, 2009 #4


    Staff: Mentor

    Can you be more specific about what you're trying to do? This doesn't make any sense to me. An ordinary graph of a function y = f(x) is a plot of the points (x, y) that satisfy the equation y = f(x). Are you trying to see what you get when you plot the pairs (x, y^2)?
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