我正在Laravel 5.8中創建一個新項目，我也想安裝Telescope，但是當我在項目中執行命令時：composer require laravel/telescope輸出：./composer.json has been updated Loading composer repositories with package information Updating dependencies (including require-dev) Your requirements could not be resolved to an installable set of packages.  Problem 1    - laravel/telescope 2.0.x-dev requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - laravel/telescope v2.0 requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - laravel/telescope v2.0.1 requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - laravel/telescope v2.0.2 requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - laravel/telescope v2.0.3 requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - laravel/telescope v2.0.4 requires moontoast/math ^1.1 -> satisfiable by moontoast/math[1.1.0, 1.1.1, 1.1.2].    - moontoast/math 1.1.2 requires ext-bcmath * -> the requested PHP extension bcmath is missing from your system.    - moontoast/math 1.1.1 requires ext-bcmath * -> the requested PHP extension bcmath is missing from your system.    - moontoast/math 1.1.0 requires ext-bcmath * -> the requested PHP extension bcmath is missing from your system.    - Installation request for laravel/telescope ^2.0 -> satisfiable by laravel/telescope[2.0.x-dev, v2.0, v2.0.1, v2.0.2, v2.0.3, v2.0.4].  To enable extensions, verify that they are enabled in your .ini files:如何安裝缺少的依賴項？我正在使用PHP 7.2和ubuntu 18.04.2。