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    1 ##DESCRIPTION
    2 ##Calculus: Differentiation
    3 ##ENDDESCRIPTION
    4 
    5 ##KEYWORDS('calculus', 'differentiation')
    6 ##Tagged by YJ
    7 
    8 ## DBsubject('Calculus')
    9 ## DBchapter('Differentiation')
   10 ## DBsection('Derivatives of Polynomial and Exponential Functions')
   11 ## Date('5/26/2005')
   12 ## Author('Jeff Holt')
   13 ## Institution('UVA')
   14 ## TitleText1('Calculus: Early Transcendentals')
   15 ## EditionText1('5')
   16 ## AuthorText1('Stewart')
   17 ## Section1('3.1')
   18 ## Problem1('56')
   19 
   20 ## TitleText2('Calculus: Early Transcendentals')
   21 ## EditionText2('6')
   22 ## AuthorText2('Stewart')
   23 ## Section2('3.1')
   24 ## Problem2('')
   25 
   26 DOCUMENT();        # This should be the first executable line in the problem.
   27 
   28 loadMacros("PG.pl",
   29            "PGbasicmacros.pl",
   30            "PGchoicemacros.pl",
   31            "PGanswermacros.pl",
   32            "PGauxiliaryFunctions.pl",
   33            "extraAnswerEvaluators.pl");
   34 
   35 $r1 = random(1,9,1);
   36 $r2 = random(1,9,1);
   37 while ($r1 == $r2) {
   38     $r2 = random(2,9,1);
   39 }
   40 
   41 TEXT(beginproblem());
   42 
   43 TEXT(EV2(<<EOT));
   44 Let
   45 \[ f(x) = |x - $r1| + |x + $r2|. \]
   46 Use interval notation to indicate the values of \(x\) where \( f \)
   47 is differentiable.
   48 $BR
   49 $BBOLD Note: $EBOLD When entering interval notation in WeBWorK, use
   50 $BBOLD I $EBOLD for \(\infty\), $BBOLD -I $EBOLD for \(-\infty\),
   51 and $BBOLD U $EBOLD for the union symbol.  If the set is empty,
   52 enter $BBOLD (0,0) $EBOLD.
   53 $PAR
   54 Domain = \{ans_rule(25)\}
   55 $PAR
   56 $PAR
   57 EOT
   58 
   59 $ans = "(-I,-$r2)u(-$r2,$r1)u($r1,I)";
   60 
   61 ANS(interval_cmp($ans) );
   62 
   63 ENDDOCUMENT();        # This should be the last executable line in the problem.