LINEAR EQUATION:

"); //enter the Equation var equation=prompt("Please enter equation without space and special character here (for exsample 3X+1=4 , 3x-1=5 , 1+3X=4 , 5-3x=2 , 3X=3 , 3=3X , 4=3X+1 , 4=1+3X):"); /*check space and special character*/ if (equation.indexOf(' ')>0|| equation.indexOf('$')>=0|| equation.indexOf('#')>=0|| equation.indexOf('@')>=0|| equation.indexOf('!')>=0|| equation.indexOf('&')>=0|| equation.indexOf('?')>=0|| equation.indexOf('/')>=0|| equation.indexOf('^')>=0|| equation.indexOf('*')>=0|| equation.indexOf('×')>=0|| equation.indexOf('÷')>=0|| equation.indexOf('%')>=0|| equation.indexOf('_')>=0|| equation.indexOf('€')>=0|| equation.indexOf('£')>=0|| equation.indexOf('¥')>=0|| equation.indexOf('.')>=0|| equation.indexOf(',')>=0|| equation.indexOf(':')>=0|| equation.indexOf(';')>=0|| equation.indexOf('₩')>=0 ) { document.write("Input linear equation : "+"

"+equation+"

" + " this equation contains space or special character
") ; } else { document.write("Input linear equation : "+"

"+equation+"

" ); id0=1; id1= equation.indexOf('x'); id2= equation.indexOf('='); id3= equation.indexOf('+'); id4= equation.indexOf('-'); //check first - if ( id4==0 ) { id0=-1; equation = equation.slice(1,equation.lenght); id1= equation .indexOf('x'); id2= equation.indexOf ('='); id3= equation.indexOf ('+'); id4= equation.indexOf ('-'); } /*write answer ax=c */ if ( (id1 "+"X=" +x+ " " );} /*write answer c=ax */ if ( (id1>id2) && (id3<0) && (id4<0) ) { a = parseInt(equation.substring(id2+1,id1)); c = parseInt (equation.substring(0,id2 )); x=c*(id0)/a; document.write("Answer 2: "+ "

"+"X=" +x+ "

" );} /*write answer ax=-c */ if ( (id10) ) { a = parseInt(equation.substring(0,id1)); c = parseInt (equation.substring(id4+1,equation.lenght )); x=c*(-1)/a*id0; document.write("Answer 3: "+ "

"+"X=" +x+ "

" );} /*write answer c=-ax */ if ( (id1>id2) && (id3<0) && (id4>0) ) { a = parseInt(equation.substring(id4+1,id1)); c = parseInt (equation.substring(0,id2 )); x=c*(id0)/a*(-1); document.write("Answer 4: "+ "

"+"X=" +x+ "

" );} /*write answer ax+b=c */ if ( (id10) && (id4<0) && (id3>id1) ) { a = parseInt(equation.substring(0,id1)); c = parseInt (equation.substring(id2+1,equation.lenght )); b = parseInt (equation.substring(id3+1,id2 )); x=(c-b)/a*(id0); document.write("Answer 5: "+ "

"+"X=" +x+ "

" );} /*write answer ax-b=c */ if ( (id10) && (id3>id1) ) { a = parseInt(equation.substring(0,id1)); c = parseInt (equation.substring(id2+1,equation.lenght )); b = parseInt (equation.substring(id4+1,id2 )); x=(c+b)/a*(id0); document.write("Answer 6: "+ "

"+"X=" +x+ "

" );} /*write answer b+ax=c */ if ( (id10) && (id4<0) && (id3 "+"X=" +x+ " " );} /*write answer b-ax=c */ if ( (id10) && (id4 "+"X=" +x+ " " );} }

Linear equation - Линейное уравнение