InequalityEvaluators

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Inequalities as Answers


This is the essential code for having inequalities as student answers.

Problem Techniques Index

PG problem file Explanation
DOCUMENT();

loadMacros(
"PGstandard.pl",
"contextInequalities.pl",
"PGcourse.pl",
);

TEXT(beginproblem());

Initialization: Include the macro file contextInequalities.pl.

Context("Inequalities");
Context()->variables->add(y=>"Real");
# Context()->constants->add(EmptySet => Set());
# Context()->flags->set(noneWord=>"EmptySet");

# f(x) = x^2 - 16 on -1 <= x <= 5

$range = Compute("-16 <= y <= 9");

Setup: Using Context("Inequalities"), if the student enters either the inequality -16 <= y <= 9 or the interval [-16,9] their answer will be marked correct. To mark only the inequality correct but not the interval, use Context("Inequalities-Only"); instead. Uncommenting the lines containing EmptySet creates an empty set as a named constant and uses that name.

As of January 2010, the inequality is not variable-specific, so the answer -16 <= x <= 9 would also be marked correct. We could have required students to use the variable y by removing the default variable x from the context using Context()->variables->are(y=>"Real");.

For a list of all available options for the interval context, see the POD documentation at http://webwork.maa.org/doc/cvs/pg_CURRENT/macros/contextInequalities.pl

BEGIN_TEXT
What is the range of  
\( y = f(x) = x^2 - 16 \) on the domain \( -1 \leq x \leq 5 \)?
Enter your answer using inequalities or intervals.
$BR
$BR
Range: \{ ans_rule(20) \}

END_TEXT

Main Text: The problem text section of the file is as we'd expect.

ANS( $range->cmp() );

ENDDOCUMENT();

Answer Evaluation: As is the answer.

Problem Techniques Index