PHP da massiv elementlarini tsikllarda yig'ish

php<?php
  $arr = [1, 2, 3, 4, 5];
  $res = 0;
  
  foreach ($arr as $elem) {
    $res += $elem;
  }
  
  echo $res;
?>

Задание 1

Massiv berilgan:

php<?php
  $arr = [2, 5, 9, 3, 1, 4];
?>

Ushbu massiv elementlari yig'indisini toping.

Задание 2

Massiv berilgan:

php<?php
  $arr = [2, 5, 9, 3, 1, 4];
?>

Juft sonlar bo'lgan elementlar yig'indisini toping.

Задание 3

Massiv berilgan:

php<?php
  $arr = [2, 5, 9, 3, 1, 4];
?>

Ushbu massiv elementlari kvadratlari yig'indisini toping.

Задание 4

Massiv berilgan:

php<?php
  $arr = [2, 5, 9, 3, 1, 4];
?>

Ushbu massiv elementlari ko'paytmasini toping.