在線一元二次方程式計算器實例分享，大家參考使用吧
代碼如下: <html> <head> <meta http-equiv="Content-Type" content="text/html" charset="utf-8"> <title>在線一元二次方程式計算器</title> </head> <body> <form name="fquad"> <p align="center">解二次方程式計算<br> </p> <table align="center"> <tbody> <tr> <td bgcolor="#990000"> <h2><font color="#ffffff"><input size="4" name="fa" type="text"> x<sup>2</sup>+ <input size="4" name="fb" type="text"> x + <input size="4" name="fc" type="text"> = 0 <input onclick="checkQuad()" type="button" value="解題"> <input type="reset" value="重置"> </font></h2> <p align="center"><font color="#ffffff" face="Arial"><b>一元二次方程的解法</b></font></p> </td> </tr> <tr> <td bgcolor="#990000"> <h2><font color="#ffffff">x<sub><a style="text-decoration: none" ><font color="#ffffff">1</font></a></sub>=<input size="45" name="x1" type="text"> <br> x<sub>2</sub>=<input size="45" name="x2" type="text"> </font></h2> </td> </tr> <tr> </tr> </tbody> </table> </form> <p align="center">Made by CRoot</p> <script language="JavaScript"> <!-- var rootparti; var rootpart; var det; var rootparti1; var rootparti2; var a; var b; var c; var x1; var x2; var i = "i"; function checkQuad() { var a = document.fquad.fa.value; var b = document.fquad.fb.value; var c = document.fquad.fc.value; if (a == 0 && c != 0) { x1 = -c / b; x2 = "Not a quadratic equation, but here is your answer for x"; document.fquad.x1.value=x1; document.fquad.x2.value=x2; } else if (a == "" && c != 0) { x1 = -c / b; x2 = "Not a quadratic equation"; document.fquad.x1.value=x1; document.fquad.x2.value=x2; } else { quad(); } } function quad() { var a = document.fquad.fa.value; var b = document.fquad.fb.value; var c = document.fquad.fc.value; det = Math.pow(b,2) - 4 * a * c; rootpart = Math.sqrt(det) / (2 * a); rootparti = (Math.sqrt(-det) / (2 * a)) + i; if (parseFloat(rootparti) < 0) { rootparti1 = rootparti; rootparti2 = (-1 * parseFloat(rootparti)) + i; } else { rootparti1 = (-1 * parseFloat(rootparti)) + i; rootparti2 = rootparti; } if (rootparti1 == "1i") { rootparti1 = i; rootparti2 = "-i"; } else if (rootparti1 == "-1i") { rootparti1 = "-i"; rootparti2 = i; } if (det == 0) { x1 = x2 = -b / (2 * a); } else if (det > 0) { x1 = (-b + Math.sqrt(det)) / (2 * a); x2 = (-b - Math.sqrt(det)) / (2 * a); } else if ((-b / (2 * a)) == 0) { x1 = rootparti1; x2 = rootparti2; } else { x1 = (-b / (2 * a) + " + " + rootparti1); x2 = (-b / (2 * a) + " + " + rootparti2); } document.fquad.x1.value=x1; document.fquad.x2.value=x2; } // will solve for complex numbers // --> </script> </body> </html>