php syntax error, unexpected T_VARIABLE

code:

public function isQuestion($query){

    $questions = $this->getAllQuestions();


    if (count($questions)){
            foreach ($questions as $q){
                if ($this->isQuestion$q($query)){
                    return $this->isQuestion$q($query);
                }
            }
        }

    return false;

}

error:

Parse error: syntax error, unexpected T_VARIABLE in /Applications/XAMPP/xamppfiles/htdocs/ai/application/models/question_model.php on line 7

the problem occurs on

if ($this->isQuestion$q($query)){

return $this->isQuestion$q($query);

i have some functions like isQuestion1, isQuestion2, isQuestion3 etc... and i call another function *getAllQuestions* that will return me all the numbers of the questions in an array like 1,2,3,4,5... then i use the above code to check if each function is a question based on a query