View source for FQT Using variables in text and text equations

[https://docs.moodle.org/33/en/Formulas_question_type < Formulas question type]

==Using variables in the text==

It is easy to insert values of variables directly in the text. All that is needed is to enclose the variable names with <span style="font-family:monospace;font-size:113%;">{ }</span>. Each text field has a scope of variables. All variables x of either number or string in the scope of the text can be used to replace the corresponding placeholder <span style="font-family:monospace;font-size:113%;">{x}</span> in the text.

It is also possible to evaluate an expression and insert its value directly in the text by adding an equal sign at the beginning of the bracket such as <span style="font-family:monospace;font-size:113%;">{=x/1000}</span>. This way is simpler if the named variables are not required. However, no error check is done unless the question is being instantiated in the quiz. An example is the rescaling of meters to kilometers below:

<pre style="font-size:113%;width: 98%;">
What is the speed of the rocket if it travels with distance {=x/1000} km in {t} s?
</pre>

==Using variables in text equations==

Text equations are mathematical expressions or equations that are displayed in the text using math syntax such as:
*[http://www.tug.org/ TeX]
*[https://www.w3.org/TR/MathML3/ MathML]
*[http://asciimath.org/ AsciiMath]

See [https://docs.moodle.org/32/en/Mathematics#Equation_Construction_and_Display Equation Construction and Display] for additional information on writing mathematical expressions. 

Values of variables can be inserted in text equations in the same way as in the text, that is, by enclosing the variable names with {}. Values of expressions such as {=x/1000} can also be inserted.

<div style="border:1px solid #bce8f1;border-radius:4px;padding: 0px 15px 0px; margin:20px 0 25px;">
<div style="font-family:Lucida Sans Unicode;font-size:113%;color:#6c336d;margin:10px 0 10px;> Example</div>

Write the following equation in TeX syntax. Upon display, {a}, {b} and {c} will be substituted by the value of these variables:

::{a}''x''<sup>2</sup> + {b}''x'' + {c} = 0

<pre style="font-size:113%;width: 98%;>
\( {a} x^2 + {b} x + {c} = 0 \)
</pre>

</div>

<div style="border:1px solid #bce8f1;border-radius:4px;padding: 0px 15px 0px; margin:20px 0 25px;">
<div style="font-family:Lucida Sans Unicode;font-size:113%;color:#6c336d;margin:10px 0 10px;> Example</div>

Write the following equation in MathML syntax. Upon display, {a}, {b} and {c} will be substituted by the value of these variables:

::{a}''x''<sup>2</sup> + {b}''x'' + {c} = 0

<pre style="font-size:113%;width: 98%;">
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»
  «mn»{a}«/mn»
  «msup»«mi»x«/mi»«mn»2«/mn»«/msup»
  «mo»+«/mo»
  «mn»{b}«/mn»
  «mi»x«/mi»
  «mo»+«/mo»
  «mn»{c}«/mn»
  «mo»=«/mo»
  «mn»0«/mn»
«/math»
</pre>

MathML equations are usually created with the aid of an editor. When creating the equation with an editor, it is easier to write a number, say 99, in lieu of the variables, for example:

<pre style="font-size:113%;width: 98%;margin-top:0px;">
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»
  «mn»99«/mn»
  «msup»«mi»x«/mi»«mn»2«/mn»«/msup»
  «mo»+«/mo»
  «mn»99«/mn»
  «mi»x«/mi»
  «mo»+«/mo»
  «mn»99«/mn»
  «mo»=«/mo»
  «mn»0«/mn»
«/math»
</pre>
and then replace the numbers 99 by the variables {a}, {b} and {c} in the HTML code.

</div>

<div style="border:1px solid #bce8f1;border-radius:4px;padding: 0px 15px 0px; margin:20px 0 25px;">
<div style="font-family:Lucida Sans Unicode;font-size:113%;color:#6c336d;margin:10px 0 10px;> Example</div>

Write the following equation in the AsciiMath syntax. Upon display, {a}, {b} and {c} will be substituted by the value of these variables:

::{a}''x''<sup>2</sup> + {b}''x'' + {c} = 0

<pre style="font-size:113%;width: 98%;">
<script src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=AM_HTMLorMML"></script>
`{a} x^2 + {b} x + {c} = 0`
</pre>
</div>

<div style="border:1px solid #bce8f1;border-radius:4px;padding: 0px 15px 0px; margin:20px 0 25px;">
<div style="font-family:Lucida Sans Unicode;font-size:113%;color:#6c336d;margin:10px 0 10px;> Example</div>

Use variables and expressions in text equations that appear in the main question text, the general feedback and the part's feedback of a Formulas question. Use MathML syntax.

''Downloadable question file:'' [https://drive.google.com/open?id=1MVUhvncCMHYl3LM-XpklggV-bpku5L8v QuadraticEquation.xml]

This Formulas question looks like this:

[[File:QuadraticEquation.png|695px]]

</div>


[https://docs.moodle.org/33/en/Formulas_question_type < Formulas question type]
[[Category:Formulas question type]]