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Graphing problem

  1. Jun 21, 2004 #1
    HI, please lend me some hints on how to graph the following equation in terms of y.

    x = y + sin[y]

    I know to plot it in terms of y, i should simply switch the places of y's and x's:

    y = x + sin[x]

    but i don't know how it looks like on the graph. Any idea how?

    Appreciate it!
  2. jcsd
  3. Jun 21, 2004 #2
    There are two ways to figure out what the graph looks like: (1) Get some graphing software and have it do it for you (2) or do it yourself. If you will do it yourself, I suggest you first draw a table of values (one column for the independent variable(s) and another for the dependent variable). After that, just plot the values in cartesian space.

    The graph of x = y + sin y looks like the graph of x = y except that instead of having a straight line, you have a sinosoudial (is that spelled right?) one.
  4. Jun 21, 2004 #3
    Alternatively, for the graph of a sum of two functions, you could plot each individually and then kind of eyeball add them. For instance, your example

    f(y) = y + sin(y)

    Notice that f(y) is the sum of two functions, i.e. y and sin(y).

    So you'd plot g(y) = y and h(y) = sin(y). Then you'd add them by thinking that the length between the horizontal axis and h(y) should be added to the length between the horizontal axis and g(y).

  5. Jun 21, 2004 #4
    Or you could find the first and second derivative, use the first for increasing vs. decreasing and the second for concavity.
  6. Jun 21, 2004 #5


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    Science Advisor

    I know what it means to "graph a function". What do you mean by "graph in terms of y"?
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