1.php

<?php
function equation($a, $b, $c){
    if ($a != 0){
        $D = $b*$b - 4*$a*$c;
        if($D < 0){
            return "No roots";
        }
        if($D == 0){
            return -$b/(2*$a);
        }
        if($D > 0) {
            $x1 = (-$b + sqrt($D)) / (2*$a);
            $x2 = (-$b - sqrt($D)) / (2*$a);
            return array($x1, $x2);
        }
    }
    else{
        if($b==0) return "No roots";
        return -$c*$b;
    }
}
$res = equation(6,0,0);
if(gettype($res) == "array"){
    foreach ($res as $i) echo "Root: ".$i."</br>";
}
else print $res;