Roots of Quadratic Equation: JavaScript

Quadratic Equations are of the form ax² + bx + c = 0. To find roots(root1 and root2) of such an equation, we need to use the formula

Video Explaining The JavaScript Code To Find Roots of a Quadratic Equation:

To calculate the roots of a quadratic equation using a computer program, we need to break down the formula and calculate smaller parts of it and then combine to get the actual solution.

So lets calculate square root of b² – 4 * a * c and store it in variable root_part. Also store 2 * a in variable denom. Now calculate ( – b + root_part ) / denom and store it in root1 and ( – b – root_part ) / denom in root2.
Output the values of root1 and root2 to the browser using document.write statement.

Javascript Coding Explained In Above Video:

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 <title>Quadratic Equation</title>
 
 
<script type="text/javascript">
<!--
var a = prompt("Enter value of a","1");
var b = prompt("Enter value of b","4");
var c = prompt("Enter value of c","4");
 
var root_part = Math.sqrt(b * b - 4 * a * c);
var denom = 2 * a;
 
var root1 = ( -b + root_part ) / denom;
var root2 = ( -b - root_part ) / denom;
 
document.write("1st root: "+root1+"<br />");
document.write("2nd root: "+root2+"<br />");
 
// -->
</script>

Usually people will make mistake in this line

var root_part = Math.sqrt(b * b - 4 * a * c);

Be sure that, you write capital letter M in Math.sqrt.

Work Space:
Quadratic Equation: ax² + bx + c = 0
Let,
a = 1
b = 4
c = 4
i.e., 1x² + 4x + 4 =0
=> 1x² + 2x + 2x + 4 = 0
=> x ( x + 2 ) + 2 ( x + 2 ) = 0
=> ( x + 2 ) + ( x + 2 ) = 0
=> x + 2 = 0 AND x + 2 = 0
=> x = -2 AND x = -2