59            throw new \InvalidArgumentException(
"Coefficient a cannot be 0!");
 
   61        $discriminant = $b ** 2 - 4 * $a * $c;
 
   62        if($discriminant > 0){ 
 
   63            $sqrtDiscriminant = sqrt($discriminant);
 
   65                (-$b + $sqrtDiscriminant) / (2 * $a),
 
   66                (-$b - $sqrtDiscriminant) / (2 * $a)
 
   68        }elseif($discriminant == 0){