Merge pull request #1021 from gajennings/main

Fix bug 4749.  Require interval notation.

Author: gajennings

OpenProblemLibrary/CollegeOfIdaho/setAlgebra_04_02_CompoundIneq/42IntAlg_21_CompoundIneq.pg

@@ -23,7 +23,6 @@ loadMacros(
   "PGstandard.pl",
   "PGchoicemacros.pl",
   "MathObjects.pl",
-  "contextInequalitiesAllowStrings.pl",
   "PGcourse.pl"
 );
 
@@ -33,6 +32,8 @@ TEXT(beginproblem());
 #  Setup
 #This is an (-infinity,a) or (b,infinity) problem:
 
+Context("Interval");
+
 $a = random(-5,4,1);
 do {$b = random(1,9,1);} while ($a==$b);
 
@@ -42,19 +43,25 @@ do {$b = random(1,9,1);} while ($a==$b);
 ######################################
 #  Main text
 
+Context()->texStrings;
 BEGIN_TEXT
-Solve the compound inequality. 
+Solve the compound inequality. Write your answer in \{helpLink("interval","interval notation")\}.
 \[ $inequal[$slice[0]] \mbox{ or } $inequal[$slice[1]] \]
-Answer:  \{ ans_rule(20) \}
+Answer:  \(x \in \) \{ ans_rule(20) \}
 END_TEXT
+Context()->normalStrings;
 
 ######################################
 #  Answer
 
-Context("Inequalities-AllowStrings");
+# Require interval notation so answers don't just repeat the question. 
 
-$ans = Compute("$inequal[0] or $inequal[1]"); 
-if ($a>$b) {$ans = Compute("All real numbers");}
+if ($a<$b){
+  $ans = Compute("(-infinity,$a) U ($b,infinity)");
+} 
+else {
+  $ans = Compute("(-infinity,infinity)");
+}
 ANS($ans->cmp);	
 
 $showPartialCorrectAnswers = 1;