HW help in calc: SOLVED

Discussion in 'Off Topic' started by optimistic, Oct 16, 2001.

  1. optimistic

    optimistic Diamond Member

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    Show by means of an example that lim x->a [f(X) + g(x)] may exist even though neither lim x->a f(x) nor line x->a g(X) exists.


    hi thanks for your interest
     
  2. notfred

    notfred Lifer

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    $f = "lim x->a f(x)";
    $g = "line x->a g(X)";
    $lim = "x->a [f(X) + g(x)]";

    $f =~ s/[ -}]//g;
    $g =~ s/[ -}]//g;

    if ($f ne ''){print "limit exists\n"}
    else{print "limit doesn't exist\n"}

    if ($g ne ''){print "limit exists\n"}
    else{print "limit doesn't exist\n"}

    if ($lim ne ''){print "limit exists\n"}
    else{print "limit doesn't exist\n"}
     
  3. optimistic

    optimistic Diamond Member

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    When adding to infite limits. Fcn's alone are defined as infinite or DNE. When adding to infite you get infite.

    Duh! RYan hellO?
     
  4. Capn

    Capn Platinum Member

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    exist as in a finite number?

    If that's the case then

    f(x) = 1/(2-x)

    g(x) = 1/(x-2)

    x->2 for f(x) would be +/- infinity depending on direction
    x->2 for g(x) would also be +/- infinity depending on direction

    however f(x)+g(x) equals 0, so x->2 equals 0

    Not sure if that's what you're looking for
     
  5. optimistic

    optimistic Diamond Member

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    thanks guys! you guys care.

    im just dumb. this is easy adding infinite limits..........ahhhrrrgghhhhhh..maybe i need sleep