# Create Answer Keys for Questions Using Algebraic Mode with Mathematica

To write answer keys and grading expressions for questions that use Algebraic mode with Mathematica®, you must know how to write Mathematica expressions. In addition, you should be aware of the following WebAssign-specific considerations.

## Specifying Math Variables in Answer Keys

Although not always required, you can declare your math variables at the beginning of the answer key in a comma-delimited list ending with a colon, as in the following example.

x_1, y_1, x_2, y_2: sqrt((x_1-x_2)^2 + (y_1-y_2)^2) 

Variable names in answer keys must observe the following conventions:

• Variable names must include only letters, numbers, and underscores; underscores in variable names indicate subscripting.
• Variable names are case-sensitive; X is different from x.
• Variable names should not duplicate the names of functions or of the numeric value pi.
• Variables having the names of Greek letters are displayed in mathPad and calcPad as the corresponding Greek letters. Greek letters except for π are treated as variables. The letter π is treated as a constant.
• The variable e can be used, but it will be treated as both Euler's number and as a variable name, so either response is marked correct.

The following table lists some examples.

Math Notation

x
x
x1
x1
x1
x_1
books
books
λ
lambda

Be sure that your question identifies any variables that the student should use in the answer.

## Specifying Perl Variables in Answer Keys

If you have defined a Perl variable for use in your answer key — for example, to randomize numeric values in your question — always enclose it with the <EQN> tag as in the following example:

<EQN $d>x + <EQN$e>

To avoid confusion, use different names for Perl variables and math variables in your question.

## Creating Mathematica Expressions

Most, but not all, Mathematica expressions are valid in WebAssign. Any expression that works in the WebAssign Mathematica tool will work in your question.