## Answer Blank in the Exponent

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This PG code shows how to put an answer blank in the exponent.

PG problem file Explanation

Problem tagging:

```DOCUMENT();

"PGstandard.pl",
"MathObjects.pl",
"PGcourse.pl",
"unionTables.pl",
);

TEXT(beginproblem());
```

Initialization:

```Context("Numeric")->variables->are(a=>"Real",b=>"Real");

\$n = random(3,9,1);

#  TeX
\$expression = "a^{\$n} b^{\$n}";

#  MathObjects
\$base = Formula("a*b");
\$exponent = Formula("\$n");

#
#  Display exponents nicely
#
\$w1 = 10; # width of 1st answer blank
\$w2 = 10; # width of 2nd answer blank
Context()->texStrings;
if (\$displayMode eq 'TeX') {
\$showpower =
"\( \displaystyle \$expression = (" . ans_rule(\$w1) . ")^{" . ans_rule(\$w2) . "}\)";
} else {
\$showpower =
ColumnTable(
"\( \displaystyle \$expression = \Big( \) " . ans_rule(\$w1) . " \( \Big) \)",
ans_rule(\$w2).\$BR.\$BR,
indent => 0, separation => 0, valign => "BOTTOM"
);
}
Context()->normalStrings;
```

Setup: We have a some code to display the answer blanks nicely in different modes, which you shouldn't need to change except perhaps the width for each answer blank.

```Context()->texStrings;
BEGIN_TEXT
Rewrite the following using a single exponent.
\$BR
\$BR
\$showpower
END_TEXT
Context()->normalStrings;
```

Main Text: We insert the nicely formatted answer blanks using `\$showpower`.

```\$showPartialCorrectAnswers = 1;

ANS( \$base->cmp() );
ANS( \$exponent->cmp() );
```

```Context()->texStrings;
BEGIN_SOLUTION
\${PAR}SOLUTION:\${PAR}
Solution explanation goes here.
END_SOLUTION
Context()->normalStrings;

COMMENT('MathObject version.');

ENDDOCUMENT();
```

Solution: