<SCRIPT LANGUAGE="JavaScript">
 
<!-- Begin
 
function quad(form) {
 
a=eval(form.a.value);
 
b=eval(form.b.value);
 
c=eval(form.c.value);
 
x1=-b/2/a+Math.pow(Math.pow(b,2)-4*a*c,0.5)/2/a;
 
x2=-b/2/a-Math.pow(Math.pow(b,2)-4*a*c,0.5)/2/a;
 
form.x1.value = x1;
 
form.x2.value = x2;
 
if (form.x1.value == "NaN") form.x1.value="Phương trình này vô nghiệm";
 
if (form.x2.value == "NaN") form.x2.value="Phương trình này vô nghiệm";
 
}
 
// End -->
 
</SCRIPT>
 
<center>
 
<form name=form>
 
<table border=1 cellpadding=2>
 
<tr>
 
<td colspan=2 align=center><b>Phương trình bậc hai<br>AX² + BX + C = 0</b></td>
 
</tr>
 
<tr>
 
<td>
 
<center><table border=1 width=100% cellpadding=2>
 
<tr>
 
<td align=center><b>A = </b></td>
 
<td align=center><input type=text size=6 name="a"></td>
 
</tr>
 
<tr>
 
<td align=center><b>B = </b></td>
 
<td align=center><input type=text size=6 name="b"></td>
 
</tr>
 
<tr>
 
<td align=center><b>C = </b></td>
 
<td align=center><input type=text size=6 name="c"></td>
 
</tr>
 
</table>
 
</td>
 
<td>
 
<center><table border=1 width=100% cellpadding=2>
 
<tr>
 
<td colspan=2 align=center>
 
<input type=button value="Giải" onClick="quad(this.form)"></td>
 
</tr>
 
<tr>
 
<td align=center><b>X1 = </b></td>
 
<td align=center><input type=text size=6 name="x1"></td>
 
</tr>
 
<tr>
 
<td align=center><b>X2 = </b></td>
 
<td align=center><input type=text size=6 name="x2"></td>
 
</tr>
 
</table>
 
</td>
 
</tr>
 
</table>
 
</form>
 
</center>