我正在尝试在Ubuntu 14.4上安装软件包php7.2-bcmath

sudo apt-get install php7.2-bcmath

但我不断收到此错误：

Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package php7.2-bcmath
E: Couldn't find any package by regex 'php7.2-bcmath'

我已经尝试过这些选项：

sudo apt-add-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get install php7.2-bcmath

将此添加到/etc/apt/sources.list：

deb http://security.ubuntu.com/ubuntu artful-security main universe

没有任何效果！

请帮助