How do I solve this error?-Parse error

Parse error: syntax error, unexpected ',' in D:\\xampp\\htdocs\\application\\controllers\\admin\\login.php on line 15
$useradmin = $this->login_model->validation_useradmin($this->input->post('useradmin'));
$passadmin = $this->login_model->validation_passadmin($this->input->post('passadmin'));
$captcha = $this->login_model->validation_captcha($this->input->post('capcher_code'));				            
            
	    	    
            if($useradmin, $passadmin, $captcha) //this is line 15
            {
                
            }

            if($useradmin && $passadmin && $captcha) //this is line 15
            {
               
            }