- sqrt: documentation ( source)
<?php
$a=0;
$b=0;
$c=0;
$determinant = $b * $b - 4 * ($a * $c) ; // D = b² - 4ac
echo "d = $determinant\n";
// x1 = (-b + Rac(D)) / 2a et x2 = (-b – Rac(D)) /2a
if ($determinant > 0){
$x1 = (-$b + sqrt($determinant))/ 2 * $a;
$x2 = (-$b - sqrt($determinant))/ 2 * $a;
echo "x1 = $x1\n";
echo "x2 = $x2\n";
}
if ($determinant == 0){
$x1 = $x2 = -$b/ (2 * $a);
echo "x1 = $x1\n";
echo "x2 = $x2\n";
}