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<link href='http://www.rjmprogramming.com.au/PHP/emboss_h1.css' rel='stylesheet' type='text/css'>
<title>Equation Solving via Backtracking - RJM Programming - January, 2017 ... thanks to New Century Maths Stages 5.2/5.3 page 432</title>

<script type='text/javascript'>

var helper_url="http://www.rjmprogramming.com.au/PHP/ParabolaLineGraph/parabola_lgraph.php?minval=!&maxval=!&e2=0&e1=!&e0=!&letter=!";
var one_two_six_seven=1267;
var theneedstobe='';
var needstobe='?';
var nextneedstobe='?';
var cmydiv='';
var afterthat='';
var athat=0.0;
var thethrees='';
var thenthrees='';
var thenthreei='';
var lts=0.0;
var subscore=1;
var oururl='';
var equation=location.search.split('equation=')[1] ? decodeURIComponent((location.search.split('equation=')[1]).split('&')[0]) : '';
var score=location.search.split('score=')[1] ? eval((location.search.split('score=')[1]).split('&')[0]) : 0;
var goes=location.search.split('goes=')[1] ? eval((location.search.split('goes=')[1]).split('&')[0]) : 0;

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               '[-][1-9][0-9]*([a-z][+-][0-9][0-9]*) / [1-9][0-9]* = [1-9][0-9]*',
               '([a-z][+-][0-9][0-9]*)[1-9][0-9]* / [1-9][0-9]* = [1-9][0-9]*',
               '[-][1-9][0-9]*([a-z][+-][0-9][0-9]*) + [1-9][0-9]* = [1-9][0-9]*',
               '([a-z][+-][0-9][0-9]*)[1-9][0-9]* + [1-9][0-9]* = [1-9][0-9]*',
               '[-][1-9][0-9]*([a-z][+-][0-9][0-9]*) - [1-9][0-9]* = [1-9][0-9]*',
               '([a-z][+-][0-9][0-9]*)[1-9][0-9]* - [1-9][0-9]* = [1-9][0-9]*',
               '[1-9][0-9]* = [-][1-9][0-9]*([a-z][+-][0-9][0-9]*) / [1-9][0-9]*',
               '[1-9][0-9]* = ([a-z][+-][0-9][0-9]*)[1-9][0-9]* / [1-9][0-9]*',
               '[1-9][0-9]* = [-][1-9][0-9]*([a-z][+-][0-9][0-9]*) + [1-9][0-9]*',
               '[1-9][0-9]* = ([a-z][+-][0-9][0-9]*)[1-9][0-9]* + [1-9][0-9]*',
               '[1-9][0-9]* = [-][1-9][0-9]*([a-z][+-][0-9][0-9]*) - [1-9][0-9]*',
               '[1-9][0-9]* = ([a-z][+-][0-9][0-9]*)[1-9][0-9]* - [1-9][0-9]*'
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  var letters=['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x']; // 'y','z' left for 2d Parabola usage
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   document.getElementById('ourx').innerHTML='Equation to solve for ' + letters[numis];
   document.getElementById('ourv').innerHTML='Solution for ' + letters[numis];
   letis=letters[numis];
   //alert(oureq + ' ' + letis);
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   numis=Math.floor(Math.random() * letters.length);
   oureq=oureq.replace('[a-z]','' + letters[numis]);
   document.getElementById('ourx').innerHTML='Equation to solve for ' + letters[numis];
   document.getElementById('ourv').innerHTML='Solution for ' + letters[numis];
   letis=letters[numis];
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      oureq=oureq.replace('[+-]','-');
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      oureq=oureq.replace('[+-]','+');
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   numis=Math.floor(Math.random() * 20);
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  var bits=oureq.split('='), xlts='';
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     thethrees=bits[0].split(letis)[1].trim().substring(0,1);
     thenthrees=thethrees.replace('/','*').replace('+','minus').replace('-','+').replace('minus','-');
     thenthreei=bits[0].split(letis)[1].trim().substring(1).split(')')[0].replace(' ','');
     if (bits[0].indexOf(') ') == -1) {
      afterthat=bits[0].split(')')[1].split(' ')[0];
     } else {
      afterthat=bits[0].split('(')[0];
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     nextneedstobe=bits[0].trim().split(' ')[eval(-1 + bits[0].trim().split(' ').length)];
     theneedstobe=bits[0].trim().split(' ')[eval(-2 + bits[0].trim().split(' ').length)];
     needstobe=theneedstobe.replace('/','*').replace('+','minus').replace('-','+').replace('minus','-');
     document.getElementById('pone').innerHTML='&nbsp;&nbsp;' + bits[1].trim() + '&nbsp;&nbsp;';  // + ' ?';
     athat=eval(bits[1].trim());
     xlts='(((' + bits[1].trim() + needstobe + nextneedstobe + ')/(' + afterthat + '))' + thenthrees + ('(' + thenthreei + '))').replace('(- ','-(').replace('(-','-(');;
     //alert(xlts);
     lts=eval(xlts);
     //alert(lts);
     document.getElementById('sone').value='?';
     document.getElementById('sthree').value='?';
     document.getElementById('ione').value='';
     document.getElementById('itwo').value='';
     document.getElementById('ithree').value='';
     //document.getElementById('isolution').value='';
     document.getElementById('isolution').value=''; //'thethrees,thenthreei,theneedstobe,nextneedstobe=' + thethrees + ',' + thenthreei + ',' + theneedstobe + ',' + nextneedstobe;
     document.getElementById('ione').focus();
  } else {
     thethrees=bits[1].split(letis)[1].trim().substring(0,1);
     //alert('bits[1]=' + bits[1] + ' and thethrees=' + thethrees);
     thenthrees=thethrees.replace('/','*').replace('+','minus').replace('-','+').replace('minus','-');
     thenthreei=bits[1].split(letis)[1].trim().substring(1).split(')')[0].replace(' ','');
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     } else {
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     }
     nextneedstobe=bits[1].trim().split(' ')[eval(-1 + bits[1].trim().split(' ').length)];
     theneedstobe=bits[1].trim().split(' ')[eval(-2 + bits[1].trim().split(' ').length)];
     needstobe=theneedstobe.replace('/','*').replace('+','minus').replace('-','+').replace('minus','-');
     document.getElementById('pone').innerHTML='&nbsp;&nbsp;' + bits[0].trim() + '&nbsp;&nbsp;'; // + ' ?';
      
     athat=eval(bits[0].trim());
     xlts='(((' + bits[0].trim() + needstobe + nextneedstobe + ')/(' + afterthat + '))' + thenthrees + ('(' + thenthreei + '))').replace('(- ','-(').replace('(-','-(');
     //alert('thethrees=' + thethrees + ' and thenthrees=' + thenthrees + ' and theneedstobe=' + theneedstobe + ' and needstobe=' + needstobe + ' and ' + letis + ' ' + xlts);
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     document.getElementById('sone').value='?';
     document.getElementById('sthree').value='?';
     document.getElementById('ione').value='';
     document.getElementById('itwo').value='';
     document.getElementById('ithree').value='';
     document.getElementById('isolution').value=''; // 'thethrees,thenthreei,theneedstobe,nextneedstobe=' + thethrees + ',' + thenthreei + ',' + theneedstobe + ',' + nextneedstobe;
     document.getElementById('ione').focus();
  }
  //document.title=needstobe + ' ... ' + oureq;
  //setTimeout(make_an_equation,5000);

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    oururl=oururl.replace('!','' + eval(1.0 + lts));
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    oururl=oururl.replace('!','0');
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  }
  var fis=intrm;
  var zintrm=eval(0.0 + eval(intrm));
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   oururl=oururl.replace('!','+' + zintrm);
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   oururl=oururl.replace('!','' + zintrm);
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  //if (needstobe == '-' || needstobe == '+') {
  //intrm='(-1.0 ' + thethrees + ' ((' + afterthat + ')*(' + thenthreei + ') ' + thenthrees + ' (' + onehuh + '*(' + nextneedstobe.replace(' ','') + ')' + '))' + ('/').replace('x','*') + '((' + athat + ')' + '*' + '(1.0)))'; 
  intrm='(-1.0 ' + thethrees + ' ((' + afterthat + ')*(' + thenthreei + ') ' + thethrees + ' (' + onehuh + '*(' + nextneedstobe.replace(' ','') + ')' + '))' + ('/').replace('x','*') + '((' + athat + ')' + '*' + '(1.0)))'; 
  } else {
  intrm='(-1.0 ' + thethrees + ' ((' + afterthat + ')*(' + thenthreei + '))' + ('/').replace('x','*') + '((' + athat + ')' + '*' + '(' + nextneedstobe.replace(' ','') + ')))'; 
  }
  //alert(intrm);
  var sis=intrm;
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   oururl=oururl.replace('!','+' + zintrm);
  } else {
   oururl=oururl.replace('!','' + zintrm);
  }
  //alert(fis + ' ... ' + sis + ' +++ ' + oururl);
  oururl=oururl.replace('!',letis);
}

function fixthis(huhg) {
  if (huhg.indexOf('/-') != -1) return huhg.replace('/-','/(-') + ')';
  return huhg;
}

function examine(iois) {
 if (iois.value != '') {
  if (iois.id.indexOf('one') != -1) {
    if (iois.value.trim() != ('' + nextneedstobe) || document.getElementById('sone').value != needstobe) {
      alert('Please try again.');
      iois.focus();
    } else {
      subscore++;
      document.getElementById('ptwo').innerHTML=fixthis('(' + document.getElementById('pone').innerHTML.replace(/&nbsp;/g,'').trim() + document.getElementById('sone').value.trim() + document.getElementById('ione').value.trim() + ')');
      document.getElementById('itwo').focus();
    }
  } else if (iois.id.indexOf('two') != -1) {
    if (iois.value.trim() != ('' + afterthat) || document.getElementById('stwo').value != '/') {
      alert('Please try again.');
      iois.focus();
    } else {
      subscore++;
      document.getElementById('pthree').innerHTML=fixthis('(' + document.getElementById('ptwo').innerHTML.replace(/&nbsp;/g,'').trim() + document.getElementById('stwo').value.trim() + document.getElementById('itwo').value.trim() + ')');
      document.getElementById('ithree').focus();
    }
  } else if (iois.id.indexOf('three') != -1) {
    if (iois.value.trim() != ('' + thenthreei) || document.getElementById('sthree').value != thenthrees) {
      alert('Please try again.');
      iois.focus();
    } else {
      subscore++;
      document.getElementById('psolution').innerHTML=fixthis('(' + document.getElementById('pthree').innerHTML.replace(/&nbsp;/g,'').trim() + document.getElementById('sthree').value.trim() + document.getElementById('ithree').value.trim() + ')'); // + '=';
      lts=eval(document.getElementById('psolution').innerHTML);
      document.getElementById('psolution').title='' + lts;
      document.getElementById('isolution').title='' + lts;
      document.getElementById('isolution').focus();
    }
  } else if (iois.id.indexOf('solution') != -1) {
    goes++;
    if (iois.value.substring(0,1) == '(') iois.value='' + eval(iois.value);
    if (iois.value != ('' + lts)) {
      if (Math.abs(eval(iois.value) - lts) > 0.01) {
        var huh=prompt('Please try again.  Or Cancel if too hard (and we will show you answer in webpage title), and any other answer attempt, even here, will be considered.', '0.0');
        if (huh == null) {
           document.title=document.getElementById('oureq').innerHTML + ' = ' + lts;
           make_an_equation();
        } else if (huh != '') {
           iois.value=huh;
           examine(iois);
        }
      } else {
        score+=subscore;
        make_an_equation();
      }
    } else {
      score+=subscore;
      make_an_equation();
    }
  } 
 }
}

function showiframe() {
  document.getElementById('my2dparabola').src=oururl;
  document.getElementById('my2dparabola').style.display='block';
}

function ask() {
  var yours=prompt('What is your linear equation like 6 = (g - 7)8 + 4  ?','');
  if (yours != null) {
    if (yours.indexOf('=') > 0) {
     location.href=document.URL.split('?')[0] + '?equation=' + encodeURIComponent(yours) + '&score=' + score + '&goes=' + goes;
    }
  }
}

</script>


</head>
<body onload='make_an_equation();' style='background-color:lightgreen;'>
<h1>Equation Solving via Backtracking <a onclick='ask();' style='cursor:pointer;text-decoration:none;' title='Add your own equation'>&#10133;</a></h1>
<h3>RJM Programming - January, 2017 - Thanks to New Century Maths Stages 5.2/5.3 page 432</h3>
<h4>Level of Difficulty: <select id='difficulty' onchange='one_two_six_seven=eval(this.value); make_an_equation(); '><option value='1267'>Difficult</option><option value='99'>Easier</option><option value='9'>Easy</option></select>  <h4 id='score'>Score: 0/0</h4>
</h4>
<div id='mydiv'>
<table border=20 cellspacing=4 cellpadding=20><tbody id='mytbody'>
<tr id='mytrh'><th id='ourx'>Equation to solve for </th><th>First backtracking step</th><th>Second step</th><th>Third step</th><th id='ourv'>Solution for </th></tr>
<tr id='mytr'><td id='oureq'></td><td id='one'>
<span id='pone' style='width:40%;text-align:right;'></span>
<select size=5 onchange=" if (this.value != needstobe) { alert('Please try again.'); } " id='sone' style='display:inline;background-color:yellow;width:28%;'><option value='?'>?</option><option value='*'>x</option><option value='+'>+</option><option value='-'>-</option><option value='/'>/</option></select>
<input onblur=" examine(this); " type='text' style='width:30%;background-color:pink;text-align:left;' id='ione' value=''></input>
</td>
<td id='two'>
<span id='ptwo' style='width:30%;text-align:right;font-size:12px;'></span>
<select onchange=" if (this.value != '/') { alert('Please try again.'); } " id='stwo' style='display:inline;background-color:yellow;width:28%;'><option value='/'>/</option></select>
<input onblur=" examine(this); " type='text' style='width:30%;background-color:pink;text-align:left;' id='itwo' value=''></input>
</td>
<td id='three'>
<span id='pthree' style='width:40%;text-align:right;font-size:12px;'></span>
<select size=5 onchange=" if (this.value != thenthrees) { alert('Please try again.'); } " id='sthree' style='display:inline;background-color:yellow;width:28%;'><option value='?'>?</option><option value='*'>x</option><option value='+'>+</option><option value='-'>-</option><option value='/'>/</option></select>
<input onblur=" examine(this); " type='text' style='width:30%;background-color:pink;text-align:left;' id='ithree' value=''></input>
</td>
<td id='solution'>
<span id='psolution' style='width:60%;text-align:right;font-size:12px;'></span>
<input onblur=" examine(this); " type='text' style='width:28%;background-color:pink;text-align:right;' id='isolution' value=''></input>
&nbsp;&nbsp;<br><a style="cursor:pointer;text-decoration:underline;" title='Help' onclick=" showiframe(); ">Help</a>
</td>
</tr>
</tbody></table>
</div>
<iframe src="about:blank" id="my2dparabola" style="display:none;width:100%;height:500px;"></iframe>
</body>
</html>